Why is my psp not reading UMD discs?

when you put the disc in does it spin up?

if not you may have a tough time.

does it atleast boot up?

does the PSP give any errors?

inspect the disc and see if its dirty.

check to make sure nothing is jammed in the slot of the PSP itself.

is this a UMD that worked before and just doesnt now? or is it a new game?

when was the last time the firmware was updated?

so if thats the case there are 2 versions. you need to figure out which one you have. the psp 300x or xc.

both tear down guides are on this site along with the drive needed to be replaced.

X= PSP 300x UMD Drive Replacement

XC = PSP 300xc UMD Drive Replacement

good luck my friend!