Is there a way to put my temporary crown back on?

Denture adhesive: As a very temporary measure, you could put in the temporary crown with a product such as fixodent. This will hold you over for a day or two until you can see your dentist to have it recemented. It is highly recommended to see your dentist asap, otherwise the new crown may not fit properly, you may get decay, or break the tooth.

Easiest way: Is with either fixodent or most drug stores sell a dental temporary cement. If unsure call your dentist.

Best not to unless: Your own dentist says it's ok, or the tooth is very sensitive, or you are out of town and can't find a dentist to temporarily cement it back in. I have seen too many patients try to cement it back in, only to not get it back right and end up breaking it or losing it (or swallowing it). Start by calling your own dentist to have him\her suggest what to do in your particular case.

Dentist is best bet: Obviously, your dentist is your best bet, but denture adhesive, even toothpaste has been used to temporarily affix the temporary to your tooth. If you do it yourself, remove it at night to avoid swallowing it.

Temp cement: Most pharmacies carry temporary cements for situations like this. It is important though to get back to the dentist and have the crown evaluated.