Thanks for writing. It doesn't sound like cutworm damage --- it may be a pest such as deer, rabbits, possum, raccoon, or other critters. There are several repellents on the market you can try; look for them at your local garden center, nursery, or online retailer.
If there were growth shoots under where your tomatoes were cut off, they should grow --- so your tomatoes may not be a total loss.
---Justin, Senior Garden Editor, BHG.com"