When refitting the front wheel, you wanna pack the left side of the wheel centre with thick grease, and you MUST line up the lugs of the Speedo Rotor Sensor correctly.
Easy mistake not to do it, but with no speedo and £30 odd a few days later you will learn not to do it again.
It's fiddly getting the front wheel back on but once you realize what's going on it gets much simpler.