I'd agree with the suggestion about checking for a bad earth, but the indicators are earthed through the black wire which joins all the others in the loom which are all earthed together - so I'd expect other lights not to work either - does everything else work OK? The horn for example?
If none of the indicator bulbs are lighting, and you are happy that the connectors close to the indicators are good, the problem must lie further down the loom, but do check the indicators connections to earth on the black wire first. I'd then check the connectors on the flasher relay and the connector to the handlebar switch.
As Brian says, the problem lies almost certainly with the re-assembly, maybe just a connector not properly pressed together?
If still no joy, you'll need to trace the problem from battery to indicator using a multimeter, or if you don't have one just use a small 12v bulb (like from the speedo' light) and connect to it 2 wires, one goes to the negative of the battery and, with the ignition and indicator switch turned on, use the other wire to trace the power to the indicators. When the light doesn't work, you've found the point at which the circuit is bad.