An easy way to fix the appliance is to replace the bad timer switch with a single pole, single throw toggle switch. Make sure to get one rated for 20 amp's at 120 volts AC. You will no longer have a timer and you will need to turn the oven on and off manually. These switches can be purchased at any electrical parts store or at many hardware stores for under $10.
If you want to keep the timer, there are a couple switches that you can use to replace the original switch, or you can purchase the
DKJ/1-60 switch from Italy. They are made for Delonghi toaster ovens and are readily available. One part # is
5218104600. This switch will work the same as the original but it only has about a 15 minute toast timer. Turn counter-clockwise to turn the oven On like the original switch. You may need to use some mounting parts from the old switch depending on your particular oven. Another switch which has a 120 minute timer is part #
5218101800. Both of these look the same as the DKJ/1-60 and are about the same size with the bell on the back of the switch. I’m happy to help further over the phone at
https://www.6ya.com/expert/jeremy_69f3cc28d95bf514