Startup error 0xc000021a in windows 8

[Windows Central Question]

I tried different methods in this error like, refresh pc(can't refresh),system restore (can't restore), CMD - bootrec/fixboot, bootrec/scanos.....etc. and SFC/scannow(didn't work) , I tried the startup settings where you can see F1-F9, tried safe mode to disable driver signature options but it won't work, same error pops up in the startup (0xc000021a). I tried using the windows 8 installer- repair my computer option- but startup settings is not there. i can't go to safe mode. please help how to fix this error without losing my files. THANK YOU