PHP array sort index

Question

I have a array like this

Array
(
[0] => Value1
[22] => Value2
[23] => Value3
[28] => Value4
)

Now i want that it looks like this

Array
(
[0] => Value1
[1] => Value2
[2] => Value3
[3] => Value4
)

I tried a lot of array sort methods but i dont found something that works right.