TurboTax will prepare PA Schedule W-2S for you if you say "you earned income in another state" and "your employer withheld income tax for another state." Pennsylvania wants this form and your W-2s because it does not know how much Delaware tax was withheld. You should be able to attach this as a PDF. If not, click on PA Schedule W-2S for instructions on how to fax or mail your W-2 copies. Look for HOW TO SUBMIT FORM(S) W-2, 1099-R, 1099-MISC OR OTHER DOCUMENTS.
You probably will not get back Delaware tax withheld. Delaware generally follows the “convenience of the employer rule,” meaning if your employer believes you are a Delaware employee, even if you are working from home, you have to pay Delaware tax.
You can claim a credit on your Pennsylvania tax return for tax paid to Delaware but you will have to file for both states.
