1
Are you blocked by a password in BIOS, if so, you will need to contact HP support, they will be able to provide you with the specific steps to reset the BIOS password, that is motherboard specific.
2
If you are able to change settings in BIOS, find the option to restore BIOS defaults (usually F9 key in BIOS) then go to the Boot Priority list and check if you can see the internal drive or Windows Boot Manager and set that as the primary boot device.
Save those settings and restart your laptop to check if it boots into Windows.
If not, most HP Stream laptops do not actually have an internal drive, they just have an eMMC chip on the motherboard, you will need to take your laptop to a PC Repair Shop to have that eMMC chip tested, it may have failed.