So i was thinking if i send a bitcoin transaction without the miner fee or a very low fee what will happen ? would i get the coins back eventually ? or they will just stuck there forever ! and if that happened how to do that double spend ?
Bitcoins never go into space. You will either get the transaction returned or it will be included in a block.
Less chance it will included in a block, you're too lucky if some miner inlcude your transaction, but most probably it will stay in the blockchain for a long time or maybe it will return to your sending address after several times.