How to reinstall Windows 7 a completely locked PC?

So, I am using my dad s old work laptop to game on, and it is blocked from EVERYTHING. Literally the only game I can play is Minecraft, since I can t install Steam or Terraria or CS GO or anything due to the PC being blocked from installing anything. Heck, I can t even install the latest version of Java! It s so freaking sad and I want to reinstall Windows 7 on it, but the problem is, it s even blocked from doing that! I need a BIOS pasword which I dont have access to, and opening the PC is no option as they even glued everything together so it is impossible. Any of you know a solution to thi? Bypassing the locks on everything? I really wanna install WINDOWS 7 again and do whatever I want on this PC! >:(

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