Can you explain what is happening? Are you getting any error messages? If it is not a username/password issue, generally this happens when you have a conflict of some sort.
Give the steps in this tutorial a try to eliminate any possible theme or plugins conflicts:
This is what we geeks see at the end?
Oh please......... anything but either Wordpress or Microsoft........ please, at the very least be a penguin or little devil............
If I see Microsoft, I know it's not St Peter who I'll be talking to. lol 🙂
Hope you are well away from all that terrible flooding in Texas @Muse.
Heart goes out to those folk