backup/copy your database /path/to/websolarlog/database/wsl.sdb to a save location (for example; /home/
YourUser/wslBackup/);
cp /path/to/websolarlog/database/wsl.sdb /home/YourUser/wslBackup/
check if the database is there;
ls -h /home/YourUser/wslBackup/
only go further if the database is in the directory!! Else try to backup the database again to a different folder.
Clear the /path/to/websolarlog;
mv -R /path/to/websolarlog/
download the stable release from SF;
unpack the source to /path/to/websolarlog/
unzip "/path/to/websolarlog-1.0.0-full.zip" websolarlog/\*" -d "/path/to/websolarlog"
(unzip "/path/to/archive.zip" "in/archive/folder/\*" -d "/path/to/unzip/to")
restore the database;
cp /home/YourUser/wslBackup/ to /path/to/websolarlog/database
check rights and set them right.
Now it should work again.