Hmm from today my psp wont play any umds i put in

, yesturday iplayed gta without any problems

, plz if someone know what to do plz pm me or somthing, and if you say i should contact sony plz tell me how, i live in denmark by the way.
PLZZZZ i beg you guys help out with somthing. ive got a 2.6 psp.
thanks