Why cant my gta lcs load completly on my psp?

so i have this gta lcs game for 3 2 years now and then when i havent played it for like 3 months when i had the memory stick in right when it loads (gets to) vencizko the dude with purple it stops right their doesnt even move i hear the disc making that noise meaning its reading it but it never loads 100% only like 74% so i take the memory off andit loads 100% but then some where around the game it freezes then says error reading gta lcs game and again takes forever so i try this supposably helpful thing of breaking the case and just putting the front cover and the disc leaving the back side where it reads the disc supposably it reads it faster so i tried it and its the same ol thing takes forever and i pretty sure i didnt messed it up cuz i can just put krazy glue or tape to fix it again as in putting the little case back together so please help me also i downloaded the game on my memory stick but it doesnt show JD in the gimp suit idk why b ut on my actual UMD it does show him in the gimp suit and me and my cousin lay multiplayer and he has the disc and also has the character of JD in the gimp suit so im wondering if we could still play multiplayer...by the way my psp is the silver slim one thank you for the feedback