Black screen when login part comes

Hello, good evening everyone. first of all i have a window starter laptop. i started installing cool themes and transparent taskbar and stuff. But then when i downloaded windows 10 theme it worked perfectly fine to me. i tried adding glass effect to the theme by using personalizing option but it did not work. so i then tried uninstalling the theme through the control panel but non of the icons popped up.
so i then restarted my pc >>>> safe mode >>>> then uninstalled it.
so after i restarted my pc he login screen came it was black and the cursor was there alone with the restart and shutdown option.

i therefore researched on the problem immediately.
i even tried the f8 or f12 thingy but nothing works.
abd the ctrl+alt+del

nothing works please help me