My File upload utitlity - BCP is not working properly.

I am uploading my employee data in db using BCP utility--
From two days befor it give me error syas that :
                       Cannot initialize the data source object of OLE DB provider "Microsoft.ACE.OLEDB.12.0" for linked server "(null)".
During my testing i found that it was not work with the synatx - BCP..... bcp.fmt -S (local)'
if i use BCP..... bcp.fmt -S (localhost)' then it works..
 
But that issue was from last two days... Before that it was work with BCP..... bcp.fmt -S (local)' also...
 
Please help me out..