Need help with this toilet problem?

This could be a couple things. First, does your toilet flush properly? If there is no clog and the toilet flushes properly, then you need to replace your flush valve in the toilet tank. The flush valve turns the water off when the tank is filled. Those will go bad after a while and let the water keep coming. Normally that water will go down the overflow tube and into the bowl, though. Also, check the connection of the supply line. The supply line connects the valve at the wall to the toilet. If the supply line is cut or has a bad connection, water would accumulate quickly. To have that much water, one of those must be your problem. Both are quick easy fixes. Just go to your local hardware store for those parts.