Black screen

HI GUYS IM ASKING FOR HELP,

RECENTLY I CHANGED THE HARD DISK OF MY PC BECAUSE I ACCIDENTALLY UNABLED THE USER OF THE OLD HARD DISK, I DONT HAVE ENOUGH MONEY TO BRING IT TO REPAIR, SO THE HARD DISK OF MY OTHER PC(PC THATS NOT WORKING) REPLACED THE HARD DISK OF THE PC THAT IM CURRENTLY USING, IM ONLY PLAYING WITH SAFE MODE BECAUSE AFTER LOADING WINDOWS, THE SCREEN TURNS TO BLACK, IT STOPS WHERE I NEED TO PRESS CTRL+ALT+DEL BUT THE SCREENS BLACK, I TRIED PRESSING CTRL+ALT+DEL AND IT FUNCTIONS OKAY BUT THE SCREEN IS BLACK, THERE'S NO OTHER PROBLEM OTHER THAN THAT, ITS JUST BLACK SCREEN, IT IS LIKE A NORMAL DESKTOP BUT I CANT SEE WHAT AM I DOING. NEED HELP MATE, ANYTHING WILL BE APPRECIATE THANKS.