How to modify Grub. conf

Originally, I could still Access DOS, but later I mentioned modifying grub on the Internet. the conf file is okay. I modified it myself. Now I still have DOS boot, but DOS cannot be used. I have changed it back, but I still cannot enter DOS and can only access redhat, what should I do?

I posted my grub. conf file. Can you help me check whether it can be changed? How to modify it? Thank you!

 
 

  
  
# grub.conf genetated by anaconda  
  
  
#  
  
  
#Note that you do not have to return grub after making changes  to this file.  
  
  
#NOTICE:You have a/boot partition. This means that  
  
  
#all kernel and initird.Paths are relativve to /boot/  
  
  
#.e.g root(hd0,0)  
  
  
#kernel/vmlinuz-version ro root=/dev/hda7  
  
  
#initrd/initrd-version.img  
  
  
#boot=/dev/hda  
  
  
default=0 
  
  
timeout=10 
  
  
splashImage=(hd0,0)/grub/splash.xgm.gz  
  
  
title Red Had linux(2.4.20-8)  
  
  
root(hd0,0)  
  
  
kernel(/vmlinuz-2.4.20-8 ro root=LABT=/initrd/initrd-2.4.20-   8.img  
  
  
title DOS  
  
  
root(hd0,4)  
  
  
chainloader+1  
 
 

The above is the content of the entire grub. conf file. You must help me. I knocked it all up by hand. Thank you for your kindness!