When you reinstall GTA the LCPDFR files will sitll be present.
You need to delete the following...
-all ASI files
-the files in the scrips
And any of these files (may not all be there)
-scripthook.dll
- scripthook.txt
- ScripthookDotNet.asi
-ScriptHookDotNet.txt
-dsound.dll
-xliveless.dll
Then patch it and reinstall LCPDFR
Also be sure you have the read me file not ticked and run LCPDFR installer as administrator
Hopefully it helps