No. There really was no plan for that scenario. "Operation Overlord" was in essence an "all or nothing" invasion plan. If the Allies had failed to secure a beachhead at Normandy, the only immediate option was to cease the assault (stopping all plans for the later waves of troops and supplies that had been mustered and were either enroute or about to set to sea), and attempt to retreat and regroup back in England.
Other than that, options were quite limited for an invasion of "Fortress Europe" and a breaching of Hitler's Atlantic Wall. Other potential beach landing areas around Le Havre or at Pas de Calais were even more heavily fortified than Normandy was, so if D-Day Normandy "Operation Overlord" had been a failure, those other possible invasion points across the English Channel would also not likely be successful, and attempts to land there would most likely be repelled as well by the Germans.
A failed Normandy invasion on D-Day would have been utterly disastrous of course for the Allies, with many tens of thousands of the first few waves of soldiers from the initial invasion force who did make it to the beaches, now cut off from backup and resupply after the retreat had been called, being killed or captured as the Germans swept them up off the beaches.
Supreme Commander of the Allied Expeditionary Forces in Europe, General Dwight D. Eisenhower, wrote what has now become a rather famous speech (thankfully never needing to be delivered) that was prepared in case the Normandy invasion on D-Day had failed. That speech can be found in the US archives, and reads as follows -
"Our landings in the Cherbourg-Havre area have failed to gain a satisfactory foothold and I have withdrawn the troops. My decision to attack at this time and place was based upon the best information available. The troops, the air and the Navy did all that Bravery and devotion to duty could do. If any blame or fault attaches to the attempt it is mine alone."
As for there being firm Allied backup plans on the books prior to June 6th, 1944 that were designed specifically in case the Normandy invasion was to fail, there really was not much of a backup plan laid out, as any future plans to invade France/Europe from elsewhere would depend largely on how many losses the Allies had been forced to absorb in their failed attempt at Normandy. It would have been, as I said, a situation where the Allies would retreat and try to save as many soldiers as possible, regroup in England, and then start fresh with new plans. Many historians believe that had Normandy failed, it would have taken at least a year for the Allies to properly regroup and design a new plan of attack to invade Europe.
Had Normandy failed, then trying to target Southern France for a potential landing may have then been the best bet with the highest chance of success for the Allies to try gain a foothold in France, though "best chance" would not have meant a "high chance of success" in that scenario (after a hypothetical failed D-Day "Overlord" Normandy invasion attempt). Although to be honest, had "Operation Overlord" failed, due to the fact that it would probably take at least a year before another large-scale invasion attack could be mounted by the Allies, I think it is realistic to at least consider the very high degree of possibility that we would have seen a second invasion held off and then witnessed the first atomic bombs being dropped on Germany, rather than on Japan.