The physical documentation for your life insurance policy should clearly detail the name of the beneficiary that you designated at the time that you took out the policy. If you cannot find a copy of your policy, then you should contact your insurance agent or call your insurer's toll-free customer hotline to request that the company provide you with a copy.
Many people have health conditions that cause memory loss like dementia, Alzheimer's and brain tumors. If you have one or more health conditions that have put you into a position where you can no longer manage your affairs and you have given someone like a family member, professional caregiver or lawyer your power of attorney, then you should ask that person for assistance. They might already know the answer without checking or they can do the legwork for you to find out. Keep in mind that if you do not manage your own affairs for any reason or someone else set up the policy, you might not be allowed access to this information from the insurance company without the verbal or written approval of your assigned guardian or legal representative. Even if you are allowed access, you might also have to provide, for example, a security password to your local agent or a customer service agent before the person can assist you in any way.
If you want to change the beneficiary, your insurance company will ask you to make the change in writing. Of course, there are situations where you might not be permitted to make changes without someone else's approval, such as with a power of attorney, if applicable. You might also need the permission in writing of the current beneficiary if you have an irrevocable trust in place before your insurance company can update the policy.