Call the bank you do business with and ask if they cash third party checks. Explain the situation and ask how you should proceed. Be aware that many banks have a very strict no third party check rule stemming from 9/11 and fears of terrorist attempts to launder or maneuver funds. Even if your bank refuses to cash a third party check, they may allow you to deposit the check into your account and place a hold on it until it clears.
Visit the nearest branch of the bank the check was drawn on. Be sure Uncle Ralph has endorsed the check first. You will need to endorse it and provide identification. The originating bank is more likely to cash a third party check because they can quickly determine whether or not the funds to cover the check are available.
Deposit the check through the ATM of your local bank. This comes with the risk of being refused, or being put on hold, when workers review the deposited checks. Unless you know your bank's policy it's probably not a risk you want to take.
Take Uncle Ralph with you to your bank. Make sure he has current ID. Your bank may cash the check, if he is with you and provides proper identification.
Contact the originator of the check and ask them to write a check in your name, instead. If the check is a gift or payment from a family member or someone you know well, this may be your best option.
Call the bank the check is drawn on and explain the situation. Ask what procedure you should follow to cash the check. They may have affiliates in your area that will be willing to cash the check for you.
Locate a check cashing agency. These are the same people who make payday loans. Expect to pay a percentage of the check. You may be required to have your picture taken and fill out forms to verify and record your identity and address. This can be costly. Reserve this option as a last resort.