Name the range in which you're searching as 'MyRange'
Use the following code (written extempore - so u may have to fine-tune it)
Sub FindMissing()
Dim rng as Range
Set rng=Range("MyRange"

FirstNum=rng.SpecialCells(xlCellTypeConstants, xlNumbers)
NumRow=WorksheetFunction.Match(FirstNum, rng, 0)
Num1=FirstNum-NumRow+1
Num2=Num1+Rng.Rows.Count-1
Msg=""
For i=Num1 to Num2
K=0
On error resume next
K=WorksheetFunction.Match(i,rng, 0)
If K=0 then msg=msg+cstr(i)+","
Next
If msg="" then
msg="no missing numbers"
Else
msg=msg+" are the missing nos "
End if
MsgBox (msg)
End sub
AbsNumRow=rng.Rows(NumRow).Row