Amended Return - Unemployment

My son needs to amend his return because the state never sent the 1099-G and he forgot.  Though he knows the taxes might be "returned" per turbo tax , he still needs to file that form but Turbo Tax won't allow it at this time.  So, any thoughts?   I do not want him to be "accused" of not letting the IRS know of the 1099G which no taxes were withheld.   I don't know how to manually adjust for this either.  Thank you