Meanwhile, going back to my list:
With the dragging of the multiple items, I would be able to prepare it for the renaming to the following:sample_file_1.txt
sample_file_10.txt
sample_file_11.txt
sample_file_12.txt
sample_file_13.txt
sample_file_14.txt
sample_file_15.txt
sample_file_16.txt
sample_file_17.txt
sample_file_18.txt
sample_file_19.txt
sample_file_2.txt
sample_file_3.txt
sample_file_30.txt
sample_file_31.txt
sample_file_32.txt
sample_file_33.txt
sample_file_34.txt
sample_file_35.txt
sample_file_36.txt
sample_file_37.txt
sample_file_38.txt
sample_file_39.txt
sample_file_4.txt
Samples_20.txt
Samples_21.txt
Samples_22.txt
Samples_23.txt
Samples_24.txt
Samples_25.txt
Samples_26.txt
Samples_27.txt
Samples_28.txt
Samples_29.txt
sample_file_1.txt
sample_file_2.txt
sample_file_3.txt
sample_file_4.txt
sample_file_10.txt
sample_file_11.txt
sample_file_12.txt
sample_file_13.txt
sample_file_14.txt
sample_file_15.txt
sample_file_16.txt
sample_file_17.txt
sample_file_18.txt
sample_file_19.txt
Samples_20.txt
Samples_21.txt
Samples_22.txt
Samples_23.txt
Samples_24.txt
Samples_25.txt
Samples_26.txt
Samples_27.txt
Samples_28.txt
Samples_29.txt
sample_file_30.txt
sample_file_31.txt
sample_file_32.txt
sample_file_33.txt
sample_file_34.txt
sample_file_35.txt
sample_file_36.txt
sample_file_37.txt
sample_file_38.txt
sample_file_39.txt
So, here it is a combination of both letters and numbers. It is still possible to do it via regex from this example but what if there are numbers in the parts of the file name as well; well my point it might get too complicated for a regex to do the job. And, I guess no one will argue that drag and drop arrangement of the files would take less time and is less complicated than writing regex, in my case even if I drag the files one by one.