No you do not get your points back if you lose the auction
Edit; I could've sworn in the rules it said that you do not get your point back if you lose the auction
Edit 2: If I currently have a bid on an Auction, can I also use those Points on other Auctions or in the Marketplace?
No. Points that are currently assigned to a bid on an Auction are reserved for that bid. You can use those points once/if you have been outbid on that Auction.
Can I cancel a bid on an Auction?
No. Points used in a bid cannot be retracted. Points also cannot be refunded while the Auction is live. Once an Auction ends, all points not associated with the winning bid will be returned to the non-winning Participant.
The first part just mean that you can't use the same lot of points in multiple auctions. So if you have 5K, you can't put 5K into auction one while also using that same 5K in auction 2 at the same time. Once auction one ends though, you get your points back and can use them on a different one that hasn't ended yet.
The second part means that once you enter your points into an auction, you can't cancel your bet on that auction. Either you win or you lose, but your bet is there until that auction ends.
Either way, yes, you get your points back if you lose an auction. On top of that, you get the excess points that were not needed to win back if you win an auction. For example if you bet 5,000 points, but the second highest bid was 1999 points(just as an example), you get the 3,000 points back that you didn't need to win.