My ex has a restraining order against me, based partially on lies. What can I do if he/she has convinced the kids to confirm or corroborate these lies?
Restraining orders based in part (or entirely) on lies or false allegations are not uncommon. One of the things you'll need to is to Tips On Keeping Documentation everything that happens so you can refute whatever allegations have been made. It's also crucial that you retain an attorney to contest the restraining order.
Whatever you do, don't fail to appear for the 'Show Cause' hearing (or whatever it's called in your jurisdiction). Failing to appear will practically guarantee that the order against you is granted (or continued) and the provisions specified in it will almost certainly not be to your liking or advantage.
Your goal will be to provide whatever proof you can to show that the basis for the restraining order was false, misleading, or has no merit.
If you can, speak with the children (preferably in front of a witness or your attorney) and see what they are being told to say. The restraining order may, unfortunately, prevent you from any contact with your children.
If this is the case, your attorney should attempt to speak to the children (this may or may not be allowed, depending on the restraining order) and/or with any social services or child protective agencies that may be involved. Your attorney may also want to have the allegations in the restraining order investigated, if they aren't already being investigated.