Hi Reza,
It sounds like you need to read files of "Rich Text Format." I've tried and failed to make a set of VIs that read and write RTF files. It's especially difficult because Microsoft's flavor of RTF seems a little different than other ones out there (maybe I'm wrong? I had a hard time getting it right before, though). Here's a specification in case you ever want to try to parse it:
http://support.microsoft.com/kb/86999If there is an RTF parser for LabVIEW, I'm not aware of it.
If you're specifically dealing with some format specific to WordPad, then ActiveX or .net methods are probably your best bet. (I know you've already tried ActiveX)
If you're dealing with plain text, then I agree with falkpl that all you need are the LabVIEW file IO and string functions.
I'm sorry if this didn't really help you, but I figured that it's better than nothing. If it were me, I'd just call WordPad from the command line for lack of a better solution.
Good luck,
Jim