500 Internal Server Error

I keep getting this error since few days now:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator and inform them of the time the error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.
Apache Server at usamaadil.com Port 80

I searched for this error and got to know about changing the name of .htaccess file, and i did it and my website was again running, but then again i had this error next day, and now i’ve been changing the name of file everytime, but it again starts showing up next day!