You deleted the WTF folder.
All the %% of drops you see and the items a mob drops is from MobInfo. On a fresh install (or after deleting the WTF folder) it deletes the database that you built over time.
You need to rebuild that database. All those %% you saw was what you have found over time.
If you deleted the WTF folder is it still in your recycle bin??
If so goto your current WoW install and rename the WTF folder to WTF COPY.
Open your recycle bin and navigate to the WTF folder in the recycle bin.
Right Click the WTF folder in the recycle bin and click restore.
In your WoW install directory you should now have WTF and a WTF COPY folders.
Go into the WTF folder and follow navigate these directory's --- WTF\Account\"YOUR ACCOUNT NAME"\SavedVariables\.
In there you should see MobInfo2.lua and a MobInfo2.lua.bak files.
Select those two files, right click them and select COPY (or press Ctrl+C).
Back out and goto the same location in your WTF COPY folder (WTF COPY\Account\YOUR ACCOUNT NAME\SavedVariables\.
Right Click a blank space in that folder and select PASTE (or CTRL+V).
Back out of these folders and delete the WTF folder you restored from your recycle bin.
Rename WTF COPY to WTF.
Hope this helps.
If you have already deleted your WTF folder from the recycle bin you can install
THIS DATABASE. To do this open the zip file after you download it. Inside you will find a "MobInfo2" Folder. Open your interface\addon\ folder in your WoW install directory. Drag the Mobinfo2 folder from the zip file you opened from curse gaming to your addon folder. When asked to overwrite anything say "Yes To All". Run WoW. type /mi2 in chat. Goto the database tab. Check off the box for "import only unknown Mobs". Click the red Import button. Chat will spit out some info about what MobInfo did. Your database is now pretty full. Your characters will continue to add to it as well.
When you eventually exit WoW goto your addon folder and open up the MobInfo2 folder. Delete the MI2_Import.lua file as it is no longer needed.
I know this looks like a lot but if you need any more help please do ask.