Tenses confuse me

Tenses confuse me. I am here again to bother your time to help me for these silly problems (for someon but difficult for me indeed).

1. Essential document, please keep in a save place, don’t let it be damaged or lost. Is this sentence correct and good to use?
2. A credit card got lost. Or A credit card has lost?
3. Due to the birth certificate has lost and the request for reviewing the evidence at the district has already been made, but not found it either? Or due to the birth certificate was lost and the request for reviewing the evidence at the district has already been made, but not found it either? Which one is correct or you may want to correct it to the way of your writing, please do so. Actually, I am confused about using Tenses with items 2. and 3. Please help.

Thank you and best regards,
Piakj

[RonBee]

1. Essential document, please keep in a save place, don’t let it be damaged or lost. Is this sentence correct and good to use?

Try: "This is an essential document. Please keep it in a safe place. Don't allow it to be damaged or lost."

2. A credit card got lost. Or A credit card has lost?

A credit card was lost or A credit card has been lost or Somebody lost a credit card.

3. Due to the birth certificate has lost and the request for reviewing the evidence at the district has already been made, but not found it either?

"Because the birth certificate was lost...." (I can't fathom the rest.)

:(

8)

[Tdol]

3. Due to the birth certificate has lost and the request for reviewing the evidence at the district has already been made, but not found it either?

Because the birth certificate had been lost, a request was made for the information to the district administration, who couldn't find it either.

??????