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 ?
First of all, I wouldn't suggest that you do that because it is a very stupid idea.
If a transaction goes unconfirmed for too long, it will eventually disappear from the network. Most clients will remove it from their pool of unconfirmed transactions at some point. And yes, the money should return to your account. When most clients have removed it, you can go ahead and send the transaction again, if you wish and I would suggest to use a higher fee. There's not a precise time when the transaction will disappear from the network, it could be days or up to a week. This is why it's always recommended to set a transaction fee.
That just out of his curiosity even myself having the same question back in the past when i dont really have idea on what would happen if you send bitcoin without tx fee or very very low fee. It wont really be broadcasted and possibility of getting stuck or wont confirm is there and also if you do make use of famous wallets you cant sent if you didnt follow their recommended fees even on the lowest one.