Your tubes left you in the dark, did they? That's no good!
If your tubes were working seemingly fine for any period of time (seconds, minutes or even hours) and then shut off and won't come back on, this usually points to a ballast incompatibility. The ballast may be pumping too much power into the tubes, causing them to "save themselves" by not accepting power at all.
The easiest fix for this is to remove the ballast entirely and wire the tubes to direct power. Most of our customers report an instant improvement in performance after doing so!