Asking help Ascii to Hex converter

Try the following.

Imports System.Text  
Public Class Converters  
    Public Shared Function ToHexString(sender As String) As String  
        Dim sb = New StringBuilder()  
  
        Dim bytes = Encoding.Unicode.GetBytes(sender)  
        For Each currentByte In bytes  
            sb.Append(currentByte.ToString("X2"))  
        Next  
  
        Return sb.ToString()  
  
    End Function  
  
    Public Shared Function FromHexString(sender As String) As String  
        Dim bytes = New Byte((sender.Length \ 2) - 1) {}  
  
        For index = 0 To bytes.Length - 1  
            bytes(index) = Convert.ToByte(sender.Substring(index * 2, 2), 16)  
        Next  
  
        Return Encoding.Unicode.GetString(bytes)  
  
    End Function  
End Class  

Test

Dim value = ""  
Dim hexValue = ""  
  
Dim list = new List(Of String) From {"Hello world", "This is a test", "123"}  
For Each item As String In list  
    hexValue = Converters.ToHexString(item)  
    value = Converters.FromHexString(hexValue)  
    Debug.WriteLine($"{hexValue} -> {value}")  
Next  

Did you see some threads like
Convert from ASCII to Hex Number
Text to Hex VB.Net

Since there are many free converters available to do
this task, we may assume that you are trying to code
it yourself because it is a course assignment. If that
is the case then you should NOT be using code that others
have written (although your approach may follow the same
logic and/or algorithms).

If it is an assignment, then you need to describe what
the context is of the task and any constraints.

Is the "ASCII value" a decimal number?

Or is it a printable character?

What are you expected to use?

What are you expected to NOT use?

Are you allowed to use methods/functions available
in frameworks such as .NET?

Are you expected to write VB code that implements
the conversion based on a portable algorithm
which will work when coded in any programming
language? (In the manner of number base conversions
that implement the logic without recourse to "canned"
conversion routines from libraries.)

• Wayne