I have a couple of old pots and pans laying around in the house and unfortunately I don't have the original box. Is there an easy way to tell if they are safe to use in the oven? Like for stainless steel or non-stick pans are they generally safe to use in the oven? Maybe only for certain temperatures?
Speaking in generalizations, without knowing the details of content:
Anything with a non-stick coating- I wouldn't put it in the oven. If you don't know what the non-stick coating is made of, you can't be sure if it will melt. Additionally high temperatures and non-stick coating make for off-gassing.
Anything with plastic handles, knobs or any other plastic parts- don't put it in the oven at any temperature. No way to know how it will react.
Cast iron- always oven safe to almost any temp that a non-commercial oven would reach
Enameled cast iron (like Le Crueset)- oven safe to 500°F (260°C)
Uncoated stainless steel- oven safe to 500°F (260°C)
Uncoated anodized aluminum- I would say no more than 450°F (230°C), to be safe
Copper- 500°F (260°C)
Glass- 450°F (230°C)
As an addition to Tisha's answer, if you have a soldering iron with adjustable temperature and are willing to find out if a handle is likely to melt, you can always try to apply heat to a barely visible part of the handle to gauge how high of a temperature it can withstand. Obviously if you end up doing this, do it in a well ventilated area. (This would have been a comment but I cannot post those yet)