How many 4 letter combinations containing 3 consonants and 1 vowel can be made from this set if all the letters reload in a combination must be unique?

Assuming the mathematical definition of "combination" (ie unordered sets) and the standard 26 letter Latin Alphabet as used by English:

There are 5 vowels and 21 consonants, giving:

For each vowel: a choice of 3 consonants from 21, giving 5 x 21 C 3 = 5 x (21x20x19)/(3x2x1) = 6650 combinations

[Other languages have different size alphabets and different vowel/consonants (eg Welsh, which uses the Latin Alphabet characters, has 7 vowels and 23 consonants.)]

If you have a subset of the full Latin Alphabet, or another Alphabet, then you'll need to supply the set of letters for which you wish an answer.