If you are in Windows you can go to Start > Shut Down... and select Restart in MS-DOS mode.

The computer will restart in pure DOS (not a DOS box in Windows - very important distinction).

Alternately, if your computer is already off, you can start it into pure DOS by holding down the Ctrl key or tapping the F8 key as soon as the BIOS information clears the screen. As soon as the menu appears, press the Space Bar (or any other key) once. This will keep the menu active and allow you the time to read over the selections available. Choose Command Prompt Only from the menu. You will then be in Pure DOS.

If you are having trouble booting your computer, you can use your ERD (the Emergency Recovery Disk) to boot into DOS. Simply insert the disk into the floppy drive and reboot the computer. It will do all the work for you.

Any of these choices will get you into pure DOS. Once there you can restore or even make another backup copy of the Registry.

In order to restore any copy of the Registry, either a copy you made or one that Windows 98 itself made within the last five days, just type SCANREG/RESTORE Then press the Enter key.

Using the arrow keys, select the CAB (the CABs you will see are archived copies of the Registry) you want, it is best to select one with the word Started against it, as you know that your computer booted successfully from that backup, then press Enter. The CAB files are listed by date with the most recent copy at the top. When you receive notification that you have restored a properly working registry, press ENTER to restart your computer, into windows.

If you like, you can also create another backup in DOS by typing SCANREG/BACKUP. Then follow the prompt. This backup will work exactly like the one you made in Windows. There is no functional difference.

You should now be able to boot back into Windows 98 normally, just as before you edited the Registry or had a problem.

If you have installed any software since making the backup it will be lost with the registry restore so keep that in mind.