jeeva … guess you are referring to microsoft's alarm&clock app which is included with win-10 os.
the media-file in question is located in c/windows/media directory … "Alarm01" is default. it is a *.wav file … *.mp3 files do not work. i trimmed one of my full-length *.mp3 songs
(led-zeppelin) down to a five-second file … converted that file to wav-file … this was all done online through a website called 123apps.com … which offers the free service.
now the only thing remaining was to rename
(Alarm01_old) the default-alarm so i could properly name
(Alarm01) as the newly created wav file. and this step needs security-clearance
(via permissions). one word of caution,
jeeva … altering permissions within the os
can allow hackers easy entry … altering too many parameters/permissions
could manifest unstable environment.
so … i will let you figure out that last bit of magic on your own.
i have also read there is a method utilizing the windows-registry … again, i will not share those parameters with you … for the same reason as above. let google be your ally.
ref:
edit(12-15-2016 7:50pm):
almost forgot … 123apps.com … when you download the resultant files … make sure you scan them for virus/malware … virustotal.com can be your friend in this regard.
edit(12-19-2016 7:30pm):
as so often happens … sometimes people get in over their heads when clicking this 'n that and the next thing. so, to avoid this calamity … before you start clicking
"nilly-willy" … create system-restore point. that way, you can safely return to where you started. you have the option to remove that system-restore point tomorrow … if everything is working okay.