Assuming it’s a manual transmission, have you checked the shifting linkage to make sure it’s not broken right? If you are using the clutch and it’s shifting into 1 and 2, seems that the clutch cabling is engaging fine.
This is just an example of bushings worn or the cable out of alignment: https://mercedessource.com/problems/transmission/manual-transmission-shift-linkage-binding
Basic troubleshooting for you to do:[br]
https://axleaddict.com/auto-repair/Manual-Transmission-Problems-and-Symptoms
Next time, check those first before posting as people will want photos and such. Also state the type of transmission as that’s extremely relevant to troubleshooting/diagnosing.