1. Serious hardware failure has occurred and will need to be identified and replaced.
2. Access to your files and data is likely still possible.
#1. Dismantle and identify burnt component use ifixit guide to do this and replace component
#2. Recover Data while your computer is dead.
You will need: another functional computer, or a HDD to USB converter (ATA-USB,SATA-USB), or an external hard disk enclosure.
a. Remove hard drive from broken computer using ifixit guide
b. Put hard drive into another functional computer or attach to USB converter or put in external enclosure
c. The hard drive should become accessable now copy your data off of it.
#2.I: If your hard drive does not show up or an error message is displayed you may still be able to recover your data. In this scenario it is likely that your disk file system is damaged -> cannot be mounted or booted from.
a. Test Disk: can provide access to files on a drive that cannot be mounted. Also it can often detect and recover corrupt partition tables, and recovering boot sectors.
b. PhotoRec: comes with Test Disk, PhotoRec is used to recover data that has been deleted or is on a file system that is hopelessly corrupt. It looks at the raw 1's and 0's in sequence on the drive and attempts to find file type finger prints. A word of advice: customize the recovery parameters to match only a few specific filetypes you wish to recover. This process is prone to false positives - corrupt files and will not preserve filenames.