Database issues?
Using Jamroom
It sounds like your server has run out of disk space - contact your current hosting provider and see if they can give you a bit more disk space, or find something you can delete. If all you have is JR, log in via FTP and delete all files in:
data/cache/jrCore
data/cache/ActiveSkin (the directory or your active skin).
Then see if you can log in - if you can, disable caching (ACP -> Developer -> Developer Tools -> Global Config -> Run in Developer Mode. This will prevent caching and prevent extra space from being used.
Let me know if that helps.
updated by @brian: 02/10/19 08:58:11AM