Hopefully this is completely unnecessary & you've got it handled.
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Went back to my monitored install in the XP Mode VM. ToDo Backup adds 4 drivers - eubakup.sys, EUBKMON.sys, eudskacs.sys, & EuFdDisk.sys - which are not removed with uninstall. The Agent also runs as a [stopable] service, at least one of the other files is normally in use by Windows [I think shell related], & fbnative.exe is added to the system folder.
The drivers are necessary for Windows to start -- this is unfortunate as the drivers IMHO are the most likely suspect to cause Windows to not fire up. To remove them it's 1st necessary to delete their keys in the registry -- TO do that in some cases you'll have to re-set the key's permissions. Easiest way to find them is probably searching in Regedit on the 1st part of the file names, e.g. search eubakup rather than eubakup.sys. Search for & delete EASEUS_AGENT at the same time. You may want to backup [export] any keys you delete just in case. If Windows starts normally afterwards, move the 4 drivers, & if it starts next time, delete them.
You might try Autoruns [Sysinternals at microsoft.com] to disable the drivers, but in my experience it does not always remove all the registry entries needed.
Safe Mode is your best bet *IF* the ToDo Backup drivers are causing your problem. Adding ToDo Backup may have been the last or only change that you were aware of -- that doesn't mean it's the only thing changed with Windows. Windows starts the drivers before it shows you the sign in screen, so if there's a problem Windows will not start.
If you can't get into Safe Mode because your PC/laptop hides the screen while starting, you may just be able to hit F8 intermittently during startup, or you can check your hardware's docs to disable for example their branded splash screen, or you can shut your machine off with the power button during startup, once Windows is loading but before it fails -- that should bring up a menu next time showing alternatives including Safe Mode.
Worse case scenarios would include a Windows repair install, booting to & running the Paragon Migrate OS app, or visiting reboot.pro, creating a generic WinPE type bootable disc, & using a remote registry tool to remove the drivers from the registry.