Display only numbers from Excel cell

If there are a specific number of letters, it's easy. Click on the Paste Function icon (Fx) and look for the Right, Left, Mid and or Len functions.
For instance if you have a part number ABC999,
The forumula may be
=VALUE(RIGHT(A1,LEN(A1)-3))Len determine how many characters in the string
subtract 3 for the letters and take what ever remains.
Value converts the text to numbers.

You need to be more specific with what is on your cells.
What was proposed in the previous answer holds if in general your cells have values like this:
acbdefxxxxx where x represents a number from 0-9
however if your cell have a mixture like this:
acbxxxdefxxxabcxxx that would not help.
Is there a patern? can you astablish one? if not give an example of what in your cells.