Missing Bitcoin Transaction
"Request Payment" is just a nifty little tool that generates a QR code that points to the address on the page, so it won't help you unless you want a QR code for the address. 

Check to see if the address you've sent to is in a wallet you own. If you have lost the private keys to the address, the only thing you can do is try to find them. It's nearly impossible to regain control of addresses you've lost or forgotten.