Why does my phone stay on the white T-mobile screen and doesnt change?

[AC Question]

I can not use my phone anymore. But I wanna know what I could do to fix it. One day out of the blue after I restarted my phone it just stays on the white t mobile screen and just vibrates two times every minute. I doesn't change the screen or anything it just stays that way. but what should I do to fix it?

 

[AlphaTango414]

What type of device do you have?