Random 500 server error–can't get blog back up–help!

Went to check something on my blog today, and found I’m getting a 500 Server Error on all pages, including my admin login. I’ve googled the problem had tried a few different solutions, including deleting all of my plug-ins (I couldn’t just deactivate them since I can’t access my control panel) and I’m still getting the error. This just happened out of the blue–I haven’t changed anything in the set-up, added any plug-ins, or anything else in the last few weeks, and the blog was working fine a few days ago. Have never encountered this error before.

Help?