Why can't I log into Office 365?

[Frequency]

I use Office in work and in college because I can quickly and easily share things between PCs, Laptops and my phone. Or at least, I could yesterday.

Today, I've been signed out of my desktop version of Office 365 and it will not let me sign back in. I click on sign in, it brings up the username box but when it loads the password box, it's a blank, white box.

I have uninstalled and reinstalled Office. I have updated Java and IE. I have even uninstalled and reinstalled Windows 7. It is not working.

It's not my password or subscription. I can access it on my phone and use Word Online but I need to access One Drive from my desktop and it won't let me.

All I'm getting is a message from Microsoft telling me my OS is outdated and I need to upgrade to Windows 10. Is this my only option or is there another way to make it work?

I can access Outlook from my desktop.