Bad sector in external hard drive 500 GB

hi every one hope all you are fine. 

i have external hard drive 500 GB W D(Western Digital). Problem is some of folder open and some are not. when i copy data from command prompt some of files copy and some are not. when i open it on windows then it can not open. when i open it on command prompt it can open but some of folders and files. 

My question is how can i recover it. or is it have bad sectors or any other problem 

how can i solve it. 

Thanks.