I have a 42" Toshiba flat screen. It was a floor

Electronics stores don't sell bases for TVs.

Each TV comes with one base, each base comes with a TV. The only way to get a replacement base would be to contact Toshiba and ask them directly for a replacement. For this to work, you'd need the model number of the tv. This can generally be found when you look at the back of the TV, it will have the label on a small sticker somewhere on the back.

Once you have the model number, try doing a quick search on Ebay. Someone may have an old base there that they no longer need, otherwise you're stuck with a wall mount or with contacting Toshiba.