Is my severance package still good after 4 years?

I was laid off 6/27/2012 as part of a group of employees being laid off (I believe) and I was offered a 2 week severance package. I didn’t sign it at the time. I wrote an email back 7/18/12 with a counter offer. Their lawyer replied to me 2 days after saying my employment was "at will." Two days after that the lawyer emailed me saying the "agreement is withdrawn." I didn’t reply to that email and a friend told me I could still execute the severance package agreement. Is this true? The document doesn’t specify an expiration date or anything.