Clips in project is all mixed up

Hello,

I hope someone can help. My video and audio tracks have been messed up and mixed to a serious degree.

Computersystem:                  Windows 64 bit

Version of Premiere Pro:      23.0 

The event:

I opened up my video (Premiere Pro 23.0), and it made me relocate the clips, I did this manually finding every clip, and everything seemed fine at first. 

Now everything is mixed up. Some clips have been cut short and put in 4-5 times in a row. Some clips have another clip sound, but they are linked as if the clip and sound belong to each other. 

Only the subtitles and the underlying soundtrack and logo are not messed up. 

Questions: 

- Does anyone know why it happened? 

- Can it be avoided in the future? 

- Is there a built-in safe button in Premiere Pro that will allow you to go back to a previous version of your project? 

Thank you