Reseting folder types

I have a system WIN 98 that was infected with a virus. The virus has been removed however it set some of the files types to point to it. I have fixed some (ie. scr, reg, etc) but cant change the application setting, MSDOS or MSDOS Batch as the edit button is greyed out. The filetypes are pointing to the virus app which has been removed. The result of this is I can only open apps using its releated file type (ie .doc, .eml) and cant launch the app itself as it comes it with cant find file error becauce the virus file has been deleted.
Can you help!?