I have a jumpdrive that apparently has been corrupted. I utilized Cnet download software to retrieve the files, however I cannot open the PowerPoint slides. The message that comes: No text converter for this file type--can you assist?

You may try this data recovery. I used to use it to recover my lost ppt filesafter. It works pretty well, you may give it a try.
Data Recovery - Recover Photos Songs Emails Videos and Data

What is the file format of the files you have recovered?

Apply next solution to recover powerpoint slides with all the changes were made before corruption how to fix a damaged ppt file