If your dwarf locked himself in a workshop it means that he/she work on something very cool thing, of course its random so you can't change the outcome. However the materials can vary wildy and you dont know what they require for the masterpiece. Make sure you've got lots of crafting material in your stockpiles.
If you cant procure the materials than you got two choice:
1. you can build a wall around your workshop and see that your dwarf starving to death
or
2. you can wait and see the outcome of a dwarf who after going alcohol fuelled rage, begin deliberetly decimate the population of your fortress and you will see lots of dwarfs going to throw tantrum and running berserk. This will lead the inevitable FUN!
There are a guide for the game: The Complete And Utter Newbie Tutorials by TinyPirate
