Thank you in advance.
If you are lucky, the hard drive is screwed separately. By unscrewing you can then solve and remove or replace. To what extent you have to pay attention to the type of laptop when buying the HDD, I do not know.
As? Do I have to razstun the ssd and replace it with a hdd?
Most notebooks have a separate flap on the bottom, most often labeled with the hard disk icon. Sometimes you have to unscrew the whole bottom flap.
You can find the exact procedure in the maintenance instructions, download from the notebook manufacturer.
Unscrew the underside of the notebook
Insert the HDD or SSD into the slot provided if available
Screw the notebook back
Finished
Make sure that only 2.5 inch HDDs / SSDs can be installed for space reasons.