I have a schlage dead bolt around 10years old and have difficulty putting the key in to lock or unloack
Things to try:
1. Lubricate the lock. If you think the lock is clean (not exposed to dust, rust, rain, or anything else except keys in the keyhole) then lubricate it with powdered graphite, available from most hardware stores and locksmiths. If it isn't clean, then try a shot of a lubricant that can clean it out. The cheapest is WD-40, but there are many people willing to sell you more expensive products that do the same thing that they will claim to have extra benefits. Spray it into the keyhole with a bunch of paper towels or a rag underneath to catch the stuff that comes out until it runs out clear. Try the key, and if it works, great! If not, then move on to the next step:
2. Check your key. Have you used the same key every day for 10 years? Is it worn? Is it bent or twisted? Do you have another copy that works better? If this is the only key with problems, then stop using it. Get copies made from the one that works the best, and discard the bad ones. Ideally, when you get a new lock (or car) you should make copies to use, and save the originals where you can find them again so you can make fresh copies in the future. (For a new car, copies of the electronic keys may seem expensive, but it sure beats the cost of having a locksmith fit a key to your car after you've lost both originals.)
3. If none of the above worked, your lock is probably worn. You can take the lock to a locksmith and have the pin tumblers inside replaced, or set up to work with a factory new key, but that won't replace other worn parts in the lock. You probably replaced your worn out cell phone more than twice in the last ten years, and all you did to that was press buttons on it, not stick a piece of metal in and out of it daily, slam it again and again, and expect it to protect your property and the lives of yourself and your loved ones. (Maybe you should not only replace it with the same kind, but a stronger one!)