Two options :
- your browser broke
- something broke in wordpress
Option 1 happens to me once per month in average, I don't see why. Simply deleting all of my browser's cookies mentioning my website name is enough.
Option 2 : usually, the solution is to use an FTP client to connect to your hosting account.
And then :
- first step, rename the folder of current blog theme (it's in /wp-content/themes/ ). Rename it to anything else, for instance adding an underscore _ in the beginning.
That forces wordpress to switch back to the default theme.
Did that save your blog from corruption ? If yes, your blog template was at fault.
- step 2 : rename the folders of your plugins (me, to save time, I create a new folder in /wp-content/plugins and move all of the wp-content/plugins subfolders into this new folder, this way restoring everything back is fast and easy).
That forces wordpress to deactivate all of its plugins.
Did that save your blog from corruption ? If yes, one of the plugins is the culprit, you can restore your plugin folders one by one until you find the guilty one.
If even my advice wasn't enough, then, sorry, I don't know what else to do. Reupload a fresh copy of wordpress overwriting the previous core files, maybe.