slow video playback

When I finish adding all the videos I want to edit and start editing, all the videos in Premiere play in slow motion. Even the timer runs slowly, meaning the settings are set to slow motion, not that the slow-motion effect is actually being applied. Even when I run the timer on my phone and play the video in the app, the timer in the app is slower. I don't know what the problem is exactly. I've checked the frame rate settings and everything else, but there's no result.