I can't really remember anything about my life and I'm not sure why. I've had concussion 3 or 4 times in the past. Could that have had an impact on my memory? Is this normal?

Concussions can be a serious issue, more serious than they can seem at the time. If you are experiencing memory issues and they are affecting your life, you should get yourself checked out by a doctor, though as Big Cat said, the fact you're aware of your memory lapses could be a good sign.

Even a single case of mild or moderate concussion should be taken seriously, even if they feel like nothing at the time. Studies have proven they can still be signs of damage to the brain a year after a concussion, and it is often the memory which suffers as a result of the damage.

The damage caused to the brain by concussions is becoming of greater concern in sport, where athletes, such as professional football players, can sustain repeated concussions over many years, causing permanent damage. In 2013, it was announced that hundreds of former NFL players were preparing lawsuits alleging not enough was done to protect them from brain damage caused by concussions. 

Concussions aren't the only things that affect your memory...

Of course, you could just have a bad memory. I've a friend who I've known since we were kids, and he says he can remember next-to-nothing about his school years, and is amazed when I tell him about teachers or things that happened in our classes.

If you're struggling to remember things, maybe took over old times with friends and see how much of what they say you can remember. Keeping a journal or diary may also help, as might saying things aloud while you do them, like "I am now making that doctor's appointment" before making the phone call, for example.

For more advice on how to improve your memory, check out this You Tube video, just one of many on the subject that can prove helpful: