I am not able to Open admin page and I am not even able to see any sort of errors on then page. "Service Temporarily Unavailable The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later." if i give any url of my magento site I am getting the above output. How do I resolve this? Please Help
Is your site live? are you able to access the front end of website?
please mention url
you need to check your server's error log.
if you actually see the login page and the error popups after login.
Sounds like your store have been put into mainteance mode, it should however affect the entire store not just the admin. But if it is in maintenance mode, please check for a file in the webroot, called maintenance.flag. If you remove this your store should return to normal.
I hope this helps :-)
As @Theis Corfixen said, check for the mainteance.flag file.
If that file isn't there maybe you'll need to check the var/report directory and look for any kind of report.