I have recently acquired a range that has 220 plug - the breaker box shows a double 30 amp - can I assume that that is for a range or can I convert a 110 outlet to a 220 or are there ranges that are 110. Help!

What does your current range require for power? What type of receptacles are located behind it?

What does the label on the 240V 30A breaker say it's for? When it comes to electricity, you should not assume anything. That assumption can be fatal.

120V can be converted to 240V. But you would have to know what you're doing in the panel, there could be absolutely nothing else on the circuit, and you would probably be very limited in what size breaker you could use. Much less than required for a range. This should not be considered an option.

I've never seen a 120V electric range. They may have them, but I sure haven't seen them.

A typical range is 8000 watts or larger, and needs a minimum of a 40 amp circuit, which is a 40 amp 2 pole breaker, and #8 copper wire in a 4 wire cable, and a 40/50 amp 4 wire receptacle.

Sounds like what you have is not sufficient.

You may use the 30 amp circuit, but may have problems tripping the breaker if all the range buners and oven is used all at the same time.

First what is the amp rating of your range, most that I know of require a 50 amp breaker, 30 amp is often your water heater, or air conditioner.
So what else electric is there in the place.
Was there a Gas line for a gas stove. Normal 110 wire is not going to normally carry the amps needed to work a 220 electric stove and you will need to run new wire from the box.

If you have to run a cable, make it the 4 wire #8 TKrussell said. If the 30 amp breaker keeps tripping, it will be much easier to replace later, than the cable. You can use a 30 amp breaker with #8 wire, but not #10 with a 40 amp one.