Where are music, video & document files actually stored in computer?

That's not a silly question and I believe every IT/CS engineer should understand the basics of how computer systems work. It could get embarrassing when engineers in their final year of CS/IT studies can't answer the very basic questions. A lot of self study, and reading is required by students these days.

Getting back to the question - your files are 'stored' in the HDD. But HDDs are already old and we've a new class of storage called 'SSD' aka Solid State Drives. Basically, these are your permanent storages which means they can retain data even when electricity is not applied. The read/write speed of SSD and HDDs is slower as compared to what the RAM can do.

Now, I want you to search the Internet and share your findings about RAM aka Random Access Memory. Share all the information you find online and try to figure out the exact purpose of RAM in a computer. Share your findings so that you can learn.

thank you for the reply,sir. i agree that all the files are stored on hard disk only.
that when our computer's hard disk get damaged then all the content of computer is any how get affected including backup files. but as you say SSDs are
i think very rarely used as it is new and few costly. yes solid state disks are
more reliable and faster than hard disk . and i will search and share more about RAM definitely.