Check your battery first. If the tilt won't lift or lower the motor chances are you have a dead battery or a bad connection. You could use the old trick of pouring Coca Cola on the terminals to clean up the corrosion, but for a couple of bucks you can get some battery terminal cleaner at the auto parts store. Cheaper than Coke in the long run. A good investment is a battery charger. I bought one from Wal-Mart that has a fast charge for jumping, a 10 amp for normal charging and a 2 amp for trickle charging. If you have a trolling motor you need one anyway for those batteries. For a couple of bucks you can also get a battery tester so you don't have to pull the battery out of the boat. If the battery is good and has a charge, the next step would be to check your wiring from the starter switch back.
Oh, by the way, if you do buy a charger, for safety don't charge the battery while it's in the boat unless you invest in an on board charger. (not worth the money unless you keep the boat at a dock). Hope this helps.
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Fish or Cut Bait