I works before then i can not install ce anymore, can anybody help?

and then i used # yum install i get this

[root@localhost wy]# vi /etc/yum.repos.d/kaltura.repo
[root@localhost wy]# yum clean all
Loaded plugins: fastestmirror, langpacks
Cleaning repos: Kaltura Kaltura-noarch base epel extras updates
Cleaning up everything
[root@localhost wy]# yum install kaltura-server
Loaded plugins: fastestmirror, langpacks
Kaltura | 2.9 kB 00:00
Kaltura-noarch | 2.9 kB 00:00
base | 3.6 kB 00:00
epel/x86_64/metalink | 5.1 kB 00:00
epel | 4.3 kB 00:00
https://mirrors.ustc.edu.cn/fedora/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
http://kodeterbuka.beritagar.id/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
http://mirror01.idc.hinet.net/EPEL/7/x86_64/repodata/repomd.xml: [Errno 14] curl#56 - "Recv failure: Connection reset by peer"
Trying other mirror.
epel | 4.3 kB 00:00
http://mirror.premi.st/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
http://mirror.rise.ph/fedora-epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
http://epel.scopesky.iq/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
http://ftp.jaist.ac.jp/pub/Linux/Fedora/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
http://repo.fedoralinux.ir/repos/centos/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
http://mirror2.totbb.net/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
https://epel.mirror.angkasa.id/pub/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
https://free.nchc.org.tw/fedora-epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
https://mirrors.tuna.tsinghua.edu.cn/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
http://mirrors.neusoft.edu.cn/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel | 4.3 kB 00:00
http://kartolo.sby.datautama.net.id/EPEL/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.

One of the configured repositories failed (Extra Packages for Enterprise Linux 7 - x86_64),
and yum doesn't have enough cached data to continue. At this point the only
safe thing yum can do is fail. There are a few ways to work "fix" this:

 1. Contact the upstream for the repository and get them to fix the problem.

 2. Reconfigure the baseurl/etc. for the repository, to point to a working
    upstream. This is most often useful if you are using a newer
    distribution release than is supported by the repository (and the
    packages for the previous distribution release still work).

 3. Disable the repository, so yum won't use it by default. Yum will then
    just ignore the repository until you permanently enable it again or use
    --enablerepo for temporary usage:

        yum-config-manager --disable epel

 4. Configure the failing repository to be skipped, if it is unavailable.
    Note that yum will try to contact the repo. when it runs most commands,
    so will have to try and fail each time (and thus. yum will be be much
    slower). If it is a very temporary problem though, this is often a nice
    compromise:

        yum-config-manager --save --setopt=epel.skip_if_unavailable=true

failure: repodata/repomd.xml from epel: [Errno 256] No more mirrors to try.
https://mirrors.ustc.edu.cn/fedora/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://kodeterbuka.beritagar.id/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://mirror01.idc.hinet.net/EPEL/7/x86_64/repodata/repomd.xml: [Errno 14] curl#56 - "Recv failure: Connection reset by peer"
http://mirror.premi.st/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://mirror.rise.ph/fedora-epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://epel.scopesky.iq/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://ftp.jaist.ac.jp/pub/Linux/Fedora/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://repo.fedoralinux.ir/repos/centos/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://mirror2.totbb.net/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
https://epel.mirror.angkasa.id/pub/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
https://free.nchc.org.tw/fedora-epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
https://mirrors.tuna.tsinghua.edu.cn/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://mirrors.neusoft.edu.cn/epel/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
http://kartolo.sby.datautama.net.id/EPEL/7/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
[root@localhost wy]#