It may be a dead battery, it can take a while to replenish the battery after you start it, hence it started ok then wouldnt start (it may have had just enough juice to get it going once). if you doing lots of small trips this can also kill it. try charging it or do a quick volt check across the terminals, should be a healthy 12v, if not its the battery. if you've been doing lots of long riding and its still dead (or low vaults) this can indicate a problem with the electrical charging system.
hope this helps
