In Win9x DOS 7, that location in quotes is accepted as a command parameter.
restart "G:\Abyss Web Server\database\mysql\bin\mysqld-nt" is a valid command if your DOS command is restart.com.
Or you can explore DOS and try to figure out if g:\abyssw~1 or g:\abyssw~2 is the directory you want, and build an 8.3-compatible file path without quotes.