I left fully cooked lasagna out on the counter all night. My house is 72 degrees Fahrenheit (22 degrees Celsius). Is it safe to reheat and eat?
Throw this out. The general rule of thumb is that food that isn't otherwise preserved (through large quantities of acid or sugar for example) must not be in the danger zone from 40-140 degrees Fahrenheit for more than 2 hours. In practice this is an oversimplification - see the incredible and incredibly detailed food safety section in Modernist Cuisine for the whole story. Overnight is way too long. It is quite possible for bacteria to have multiplied and secreted toxins which are heat stable. E. Coli and Staph. Aureus both do this, for example. Reheating will not make this safe. It isn't worth making yourself or your family horribly ill. Order pizza.
Was the pasta in a sealed container? If it was left open to the air or was touched by anything that could contaminate it, it might not be ok.
On the other hand, I have left rice and pasta out overnight in the pot with the lid on at room temperature numerous times and never had a problem. This "two hours at room temperature and throw it out" thing is really overkill almost all the time. Only if you are pretty unlucky will the food be unsafe to eat.
If by reheat you mean get the internal temperature up over 140F for more than 10 minutes (and it won't really taste "hot" until you do so), then it's totally fine, provided that it was fully cooked originally.
That said, if you cooked it fully originally, unless there's something a little funky about your ingredients, you're probably fine to eat it cold right now. Of course "probably" is very different than definitely.
Hence, 140F if you wish to be sure. Alternately, touching 165F would be plenty; don't even have to wait the ten minutes.