Hi Burhan,
If you launch studio for the first time, it will pop up to choose workspace in worksapce launcher wizard and it won't be popped up when launching next time if user checks 'Use this as the default and do not ask again'
Can you try killing hdbstudio.exe processes from task manager and launch studio again?
Or delete hdbstudio folder from default location say 'C:\Users\<user id>'
Best Regards,
Shireesha