registering guns

Question
Is there a way to find a gun I purchased years ago.  i purchased it but do not know the seriel number and the gun is not in my possession.  I bought a smith and weston 357 at Longs Drugs in colorado springs, colorado.  However Longs Drugs is no longer open.  

Answer
There's no practical way to find the gun, presuming that you've sold it. If the store you bought it at closed, the ATF has the paper records, but are required to keep them in paper, and would not go back through them to find the gun unless it was used in a crime (and then they would trace by known SN). Assuming you sold the gun in a private sale, no, there is no way to know where it is now.