Video in the playback window in Premiere Elements 15 runs too slow and has no sound.

Hello, I have a problem with a video in the playback window runs too slow and has no sound. I'm using Premiere Elements and I've never had this problem before.When I import it into Elements, it's in slow motion and the audio doesnt sync up at all. All older projects which play normaly are in a slow motion now and has no sounds too. When I've viewed the single clips in Windows player or VLC it's not in slow motion. I've reinstalled the program twice. Thank you