Convert ASKII to Excell

I'm afraid you'll have to go through a third party application.
Try Wordport from

http://www.acii.com

If these are really ASCII files, have you tried just opening them up in the program of choice? Likely, as DKlippert's answer suggests, they are saved in some non-windows format that will have to be converted. Often, if you have the program that made them you can save them as text-only files, which can be opened in Word or Excel (all formatting will be lost).

all the best,

Just opening the file may work, provided you have installed all the required and available converters. See control panel, add/remove software. Look for your office packet and press change. Check if under conversion programs and filters all converters are installed.
Good luck