I had about 35 GB of space left on my internal harddrive, then at some point I ftp-ed into my ps3 and removed a game off of the internal harddrive through the ftp client (mistake). When I restarted my ps3, it now shows 0 KB of space left, I tried deleting some demos and stuff through the xmb but it's stuck on 0 KB left.
My question is, is there a quick fix or do I have to format? and If I have to format, what will I lose? game saves, Homebrew apps, trophies?
Look with the FTP-App on your PS3 and search for $RECYCLE.BIN or any backup folder on the PS3-HDD. Any FTP-APPs make an Backup of Deleting files. (NOT all FTP-Apps make this or the option is normaly disabled)
And wtf you have deleted on your HDD? If you have deleted any parts of your Firmware the PS3 will not will starts normal.