So i was at windows 7 then went to windows 10 and then i decided to go back to windows 7 because of a problem (my internet wasnt working so i couldnt search it up) so i went back to windows 7 and searched it up and i want to go back but it said that windows isnt activated even though it is and when i checked my system it said 3 days untill automatic activation. activeate windows now so i did and it didnt work it just said The windows 7 ultimate product key you typed is invalid for activation. i didnt want to pay for something that i already bought. can someone help me solve this problem out?