I have a window vista home basic operating system laptop
When I open it ,it loads all its operation and it logs in( accepts user
Name and passward ) and it has only a black screen with a visible curser .
It doesnot go further( I mean it doesnot show the task bar with start menu and
All the desktop icons);

So can you help me find out the solution please..

There is a possibility that the OS(vista) is corrupted. Have you tried doing a recovery? Using the Toshiba Recovery Disk and Applications

Is it still under warranty? if so I would take it back to the retailer and ask them to fix it.

If you loaded the OS yourself, then the laptop may not be compatible with Vista. If it came with Vista loaded, then contact the manufacturer or place of purchase.