Junior grammar problem

I am confuse when I was using below tense, specially the timing….
Present prefect
Past continuous
Past prefect
Past simple
Past passive (was / were + past participle)
And any tense like:
“Are + past tense verb”?
“were + past tense verb”?

Example:
-          He has lost his key (Present prefect simple, he does not find his key yet)
-          He had lost his key (Past prefect, he already has his key back or has a new key)
-          He was losing his key (Past continuous, should be specify the time “at yesterday 10:30”)
-          He was lost his key (Past passive, ?)
-          He lost his key (Past simple, only state that he was lost his key, maybe yesterday, last month or a few month ago)

And I saw this sentence in a English course “I have repaired the washing machine”
(I realize there should be present prefect simple which means the action from the past to now and not yet finish, but how can repair washing machine still happening?)
For my understanding, it should be “I repaired the washing machine “ or “I had repaired the washing machine” or “I was repaired the washing machine”

How about below sentence, “young” should be a adj, can above tense apply to it?
-          I was young (Now I am old)
-          I had been young (And I think it’s the same meaning with above)