Unable to update software using yum in Fedora 21

edit

I am trying to update fedora 21 softwares using yum and I tried all solutions that are listed in askfedora but still I am not able to resolve it. Now I am clueless what is the issue which is causing it. The error which I get is

[root@localhost ~]# yum check-update 
Loaded plugins: langpacks
adobe-linux-i386                                                                                                               |  951 B  00:00:00     
Could not get metalink http://mirrors.fedoraproject.org/metalink?repo=fedora-21&arch=i386 error was
14: curl#7 - "Failed to connect to mirrors.fedoraproject.org port 80: Network is unreachable"
google-chrome                                                                                                                  |  951 B  00:00:00     
https://mirrors.fedoraproject.org/publiclist/Fedora/21/i386/repodata/repomd.xml: [Errno 14] curl#7 - "Failed to connect to mirrors.fedoraproject.org port 443: Network is unreachable"
Trying other mirror.
https://mirrors.fedoraproject.org/publiclist/Fedora/21/i386/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
Trying other mirror.


 One of the configured repositories failed (added from: https://mirrors.fedoraproject.org/publiclist/Fedora/21/i386/),
 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 mirrors.fedoraproject.org_publiclist_Fedora_21_i386_

     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=mirrors.fedoraproject.org_publiclist_Fedora_21_i386_.skip_if_unavailable=true

failure: repodata/repomd.xml from mirrors.fedoraproject.org_publiclist_Fedora_21_i386_: [Errno 256] No more mirrors to try.
https://mirrors.fedoraproject.org/publiclist/Fedora/21/i386/repodata/repomd.xml: [Errno 14] curl#7 - "Failed to connect to mirrors.fedoraproject.org port 443: Network is unreachable"
https://mirrors.fedoraproject.org/publiclist/Fedora/21/i386/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
[root@localhost ~]#

EDIT:

Have tried yum clean all and yum update but still same result. The output of yum repolist all is

[root@localhost yum.repos.d]# yum repolist all
Loaded plugins: langpacks
adobe-linux-i386                                                                                                               |  951 B  00:00:00     
Could not get metalink https://mirrors.fedoraproject.org/metalink?repo=fedora-21&arch=i386 error was
14: curl#7 - "Failed to connect to mirrors.fedoraproject.org port 443: Network is unreachable"
google-chrome                                                                                                                  |  951 B  00:00:00     
https://mirrors.fedoraproject.org/publiclist/Fedora/21/i386/repodata/repomd.xml: [Errno 14 ...