It should be in your tax (PDF) file, assuming you chose to save it, but I am not certain about state returns other than it may vary depending upon the state.
I have absolutely no idea whether or not anyone will accept that form as a valid legal document and/or as the tax return you filed. Again, that would most likely depend on the particular individual or organization.
It has been suggested by numerous others on this board to simply print out your 1040, sign and date it, when you need an exact copy of the return you filed.
