ahyland,
Do you mean you want all records that have values that are not within ASCII Characters 65-90 and 97-122 (the ASCII set of letters) or something else.
Your question is a bit unclear, as Mr. Bias has noted, and I'm not sure what you mean by 2, 3, and 4 character records. Either way, the only method I can think of doing this is to search each record (just one field or all fields???) individually, then look at each character individually for "non-characters" (again the verbiage is a bit unclear what you mean, because characters are always characters.....) and identify those records. With many records, fields, large strings, this could take a long time, but just about anything can be done.
Please provide an example of what you are looking for.