This question already has an answer here:

For the past few days testnet is not working properly. As of now sync is very slow and all the testnet ether is lost. I came to know all this is because of some spamming attack. Did the steps suggested here. But of not much use. My testnet chain is at 589298 and sync is at around 15 sec for each block.

what steps to do, so that testnet will start working fine.

merged by Waqar Lim Mar 6 '17 at 15:09

This question was merged with Ropsten testnet is under kind of attack? What can we do? because it is an exact duplicate of that question.