Some time its really very pain full when u have to retract the Solution files in SharePoint Development environment
this looks pretty easy if you are doing this from Central Admin but your solution does not get retracted immediately , instead it creates a timer job for you , and SharePoint knows when the timer job will run and retract your solution .
it become more frustrating , when you ran the command to retract the solution and now you want to delete the solution .
so one shot solution of all those crappy stuffs can be found here in this blog
alex thissen has explained it beautifully
go through his blog
