Sorry if i write this in wrong section, admin/mod can replace the topic in that chase.

I wanted to exchange some of my Monero to bitcoins ,at the exchange site i sent the Monero how ever it did not arrive in time so the time frame ran out, at start i could not spend anything from monero wallet duo to doubble spent error message, but the wallet still displays my coins. How ever today it says i have send the XMR and my wallet is now empty with the status of pending on the amount i tried to send to the exchange site
Where is the problem, the exchange site never got the monero it seems? But why is my wallet pending the amount and why wont it bounce back?

I use monero online wallets. Any help would be very helpful.
Im willing to pay a fee to anyone who can sort this issue and a few other crypto issues like this asap.