Compare
(A) "If Anna was here, she would've known what to do."
(B) "If Anna had been here, she would've known what to do."
In (A), the speakers are currently considering what to do and lamenting that Anna isn't with them right now, because she would have been able to help them.
In (B), the speakers are discussing a past situation (we don't know how recent) where Anna's absence left them with no solution. The opportunity to do the right thing has now passed.
I think if you see the difference between the two, that will go a long way to helping you with similar constructs.
"If you (wear) a beard all the time, they (not recognize) you without it."
All the below are possible:
(A) If you wore a beard all the time, they would not recognize you without it.
(B) If you had worn a beard all the time, they would not have recognized you without it.
(C) If you were to wear a beard all the time, they would not recognize you without it.
(A) Can be used in a past sense, in a kind of confirmatory way: Given that you always wore a beard, then of course they wouldn't recognise you without it. But it can also be a suggestion for the future: if>then.
(B) In the past period referred to, he wasn't in the habit of wearing a beard, and therefore had no chance to pass unrecognised by removing it.
(C) More specific than the second sense of (A). Making a hypothetical suggestion concerning a group of people currently unknown; implying that at the moment he doesn't wear a beard all the time (or at all).
Type 2: If she fell, she would hurt herself.
This would fit if the girl is currently on a ledge; it's describing a circumstance (being hurt) that could result from present circumstance (falling).
Type 3: If she had fallen, she would have hurt herself.
This would fit if the girl being on the ledge was a past event. It implies that she did not fall and thus did not hurt herself. This is called counterfactual statement about a past event.
Best Answer
1 is good and I can't think of anything better. 2 isn't quite right, but something like it could work, "If you didn't lose your memory, you would remember me". For example: