Why my phone open apps by itself?

@yasinebrs sounds like you maybe experiencing something called "Ghost Touch". That originates from a failure between the digitizer and the rest of the screen. You will have to replace the screen assembly. Since iFixit does not yet have a specific guide for this, use the one from here It was written in Spanish so use a browser that does the translating for you (if needed). Replacement screens are readily available and not to expensive. Just do an online search and select a vendor that appeals to you.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this. Repair is War on Entropy!