Any Function or Combination of Functions to Find Occurrence from End of String and Extract the Data

 Hi Folks

looking to find a way to find an occurrence of a character starting at the end of the string

is there any function or combination of functions that will give me that location

would like to extract out everything after the period

line may have more than one period and that is why i need to start from the end

example string(s)

this is my document.txt

this is document 2.0.txt

Thanks

Jim