My house was built in 1964. The way I found my studs was to remove the baseboard trim and I was able to see the bottoms of the studs. I made a mark in the center of each one on the drywall that would be concealed by the baseboard trim when I replaced it.

This helped establish the spacing they used when they built the house.

Then I used a 4 foot level to follow them up to the location where I needed to drill a fastener, made a mark and worked from there.

Sometimes I had to cut a bit of drywall away at the bottom to reveal the stud. That's OK, because the baseboard concealed that when I replaced it.

This works if you have trim, if you can remove it easily and if you know how to re-attach it.