Crashing, freezing, and restarting are usually signs of a software or app problem. This means your device isn't broken, but probably needs some cleanup.
Why does my Mobile keep freezing up?
There are several reasons why an iPhone, Android, or another smartphone might freeze. The culprit may be a slow processor, insufficient memory, or a lack of storage space. There may be a glitch or a problem with the software or a particular app. Often, the cause will reveal itself with the corresponding fix.
Why is my phone lagging and freezing?
If your phone is regularly slowing down or freezing, there may be an installed app that is misbehaving and taking up too much of the phone's resources. If the problems started after installing or while using a particular app, try uninstalling that app to see if it fixes the problem.