Windows Service error

Hi,

     This is what happened. There was an existing windows service which was working fine. And all of a sudden from yesterday the service stopped working. And today while i was trouble shooting, it started throwing application errors. Inorder to eliminate further errors i over written all the files including the executable on the server Which helped me in fixing the application error. Still the service is not working and throwing the errors as below 

a.) Exception OccuredSystem.NullReferenceException: Object reference not set to an instance of an object. at ExampleHawk.MailHawk.AlertsSend() in C:\data\VStudio\ExampleHawk\ExampleHawk\ExampleHawkService.cs:line 85
at ExampleHawk.MailHawk.tmrDoWork() in C:\data\VStudio\ExampleHawkHawk\ExampleHawk\ExampleHawkService.cs:line 276
at ExampleHawk.MailHawk.tmrThrdMain_Elapsed(Object state) in C:\data\VStudio\ExampleHawk\ExampleHawk\ExampleHawkService.cs:line 283
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading._TimerCallback.PerformTimerCallback(Object state)
b.)DataTableMaker ExceptionSystem.Data.SqlClient.SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
  at System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject)

Please  help !!!!!!