the first question is whether they were actually on your computer or off on the cloud somewhere
if they were on the cloud you just need to figure out where and log in again. for instance if you were looking at them with picassa that uses a gmail account to store pictures or at least can be easily set that way.
If they were on your computer in say the pictures folder than it is going to depend on how you installed the windows 10. If you did their automatic upgrade from within windows than they will be there somewhere. Even if they did not get moved to the new pictures folder they will still be in thie old one or in the section of the drive that the update reserved in case you wanted to revert to the old operating system
If on the other hand you created a flash drive or purchased the windows 10 on cd and installed that way as a clean install it would have wiped out everything on the computer.
If you did their normal upgrade from within windows i can find them for you. For a charge a lot less than you paid the other guys because i know exactly where they would be
If they were in your pictures folder than they should still be on the drive somewhere. Even if they were not moved to the new pictures folder you can find them in the old pictures folder
if you want to look yourself they would be in the C driver / users / your old login name / documents / pictures.
it might be a little different depending on what operating system you came from
or right click on the c drive and select properties
somewhere in there and i havent got it in front of me so i cant tell you exactly there is a section where it shows history and one of those will have your old stuff in it in the same place as the line above