windows 98Se

when I was re-installing windows 98, the computer frozed and installation was not completed, turn the computer back on, but gives serveral message
on the re-boot.
1. himem.sys is missing
2. divider overflow error
3. scandisk not working> freezes computer
4. command.com filled with garbage and is useless. need to reload ms dos 7.1
5. found the boot disk, but nothing works now
Help.