Generate Unique Random Strings containing Letters and Numbers (AlphaNumeric) and Numbers (Numeric) in ASP.Net using C# and VB.Net

Here Mudassar Ahmed Khan has explained with an example, how to generate unique Random Strings containing Letters and Numbers (AlphaNumeric) and Numbers (Numeric) in ASP.Net using C# and VB.Net. The unique Random Strings containing Letters and Numbers (AlphaNumeric) and Numbers (Numeric) will be generated in variable lengths such as 5, 8 and 10 characters in ASP.Net using C# and VB.Net.