In California, Labor Code Section 1198.5 gives workes the right to inspect their personal files upon reasonable notice and during normal business hours
Check your states labor code for a similar statute and follow the proceedure set forth.
Some employers will allow you to copy the entire file and some only the documents bearing your signature.
Depending on the matter you need this information for ... I would make a list of every document in the file so that if you ever go to court against your former employer and your emplolyment record becomes an issue, the list you made of the documents contained in the file could be your proof that your file was sanitized before your attorney received it.