I made an ethereum transfer between two accounts, with gas set to 21000. But the transaction is pending since the last 12 Hours and I cant see any balance being reflected in my recipient account. Please help!
Just send a new transaction and increase the gas price. The higher priced gas transaction should go through 1st.
I have tried this with Coinbase as well. I do not know which party you are transferring from, but either cancel the transfer or wait till it gets broadcasted. Sometimes the Ethereum network gets overloaded and sometimes the exchanges backend simply cannot handle all the transactions.
Something is wrong.
I suggest you to use https://www.ethgasstation.info in order to know the proper combination of gas price and gas limit In order to have the transaction executed in the time you prefer.
As a rule of thumb any transaction delay over 100 true minutes means pending transaction for ever. It means that your gas cost and gas limit combination convinced miner to evaluate and discard its execution for 400 consecutive blocks!!!