Dumb blonde needs help with power cable matching to subwoofer

MC has it right. Make sure it matches, could be a two prong or a 3 prong. 

Use a power cord that you would use in your home tower computer. It has a male plug at one end and a female at the other. It is a 3 prong plug.

Look into the plug socket of the subwoofer and see the pins and shape of the socket.  As others here who have replied have mentioned, should be a standard 3 prong plug that works for computers, one up above the two lower ones.  They are readily available at Home Depot or hardware store too.  

Another take on this is whether it matches may not be the only question. People into audio often use aftermarket power cords, since the cords that come with powered equipment are often inexpensive “standard” cords (typically all black with molded plastic ends).  It is possible your husband had some more expensive cords with his system and it would not be fair to you for a buyer to give you a fair price on a sub and then also receive an expensive power cord without paying a premium price for that.  I see you have been working on this for a couple of months so if you have somebody helping you with pricing I suggest sending them pictures of the power cords you have, and other cables, so you can get some ballpark pricing recommendations.

Every dumb blonde I ever knew, was too dumb to know she was dumb LOL