Problem with Ubuntu login with GNU GRUB

Usually, when I login, the Ubuntu login screen appears for selecting account and entering the password, but now suddenly a GNU GRUB panel appears for options like the ones shown in this image:

When I select the 1st option, it says unable to send h2c command. I googled it and I found a solution, which is to enter recovery mode in advanced options, but it was asking for login and password:

I tried with my usual credentials for Ubuntu and it says they are wrong. I don’t know why this happens.

Before this event I downloaded NVIDIA drivers (.run file), but the installation stopped in the middle (stuck). During installation, it asked to set some kind of password and I set it same as my login password. It did not ask about username.After stopping installation as it was stuck i shutdown. Next time when i login this screen appeared.
I tried with different usernames like: "root", "user", "admin", "ubuntu", "boss", but none of them worked.

Please suggest me an easy way to get out of this. I am OK to uninstall Ubuntu, but I don’t want any of the actions affect my Windows OS (dual boot on same laptop but different drives). And is there any way to remove this GNU GRUB screen? I don’t want to see this again.