Can you enable the built-in Administrator account and log into that? (You will probably need to do this from a Windows repair disc.) You can create a new user profile and move your data over to that profile then, then you may disable the Administrator account from there if you do not need it afterwards.
You may not be able to boot from a disc/disk if your BIOS has Secure Boot enabled. Disable Secure Boot, and if need be, disable UEFI temporarily. You should be able to boot from another device.