Greeting animation frozen after entering password

After i enter passwd, there will be a short animation of greeting as usual. But somehow the animation got frozen after reboot. The background animation was frozen, but the cursor was still active which followed my hand’s movement. I tried to use tty2 to restore the system but it looked failed.

The reason that caused the problem might be tty. One day i was normally writing codes. I suddenly want to try ctrl+alt+F2 to enter the tty. After I return back, the graphics system might somehow be broken with fractional GUI. I rebooted the system but it did get normal at that time.

so can you boot or you get stuck?