I'm sorry I can't go in because Ilost the key to the door

I'm sorry I can't go in because I have lost the key to the door.
首先向前面的说明下，有go in这个词组，意思是进去
只要在I和lost之间加一个have就行了 因为前面是一般进行时时态 后面用现在完成时强调对现在所造成的影响啊！

I’m sorry I can’t get in because I lost the key.
进入是用get in. 不用说明, 别人都会明白你是遗失了那道门的锁匙.

I'm sorry I can't go(go改成get) in because Ilost the key to the door

I'm sorry I can't get in because i lost the key to the door.

I'm sorry I can't get in because I lost the key to the door.

go改成come

抱歉,我进不去,因为我把钥匙弄丢了!