Turn off water, empty tank water, disconnect supply line, loosen & remove tank-to-bowl bolts. Remove tank from bowl. Hold overflow pipe and loosen spud nut under tank holding valve.
All modern toilets do not have an overflow pipe as the overflow if for instance the valve faults goes down the main soil pipe, so you can replace the cistern.
Turn off the water then remove the bolt that is underneath the toilet. Disconnect the chain and remove the refill tube. Place a new overflow pipe and flapper into the tank. It should then work perfectly.
