Start with basic tune-up.
If the bike was running fine before, it's more like a checklist. Check all fuses and relays as well. Is the battery fully charged, and holding a charge? Don't laugh, a weak battery can cause very weird symptoms that make no sense, and yes, this can appear suddenly. A weak battery can show what's looks like healthy voltage, but not under load or running conditions.
It could be the crank sensor, as mentioned above, or the TPS got moved somehow. Doubt it's the fuel pump, they tend to fail slowly.