How to open a lenovo tab that fails to open after shutting down?

I just wanna ask why did my lenovo tab 2 A7-30 can't be open after I restarted it since settings, gallery and file manager stopped. I was uploading my pics on fb and the tablet is like having a virus because it moves without me touching its screen... So I decided to remove the usb connector and open the gallery... but, it stopped... I open the file manager and it also stopped. So I open the settings, and decided to clear all the datas on gallery and file manager but the settings stopped... So I shut it down, but it won't open... What do you think is the problem of my tablet?