In validating textbox in c#.net,
I want to allow the user to enter value based on the conditions.

Not Allowed
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1. Only special characters not allowed (Ex: !@#)
2. Only Numbers not allowed (Ex: 3456)

Allowed
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3. characters only small letters allowed. (Ex: asd)
4. characters only capital letters allowed. (Ex: ASD)
5. characters having both capital and small letters allowed. (Ex: AsdF)
6. Value including Alphabets,numbers and special characters allowed (Ex: A23$, a67%)


I want these case to be implemented through RegularExpressions

Can anyone help me with ideas?,........./