It takes some effort to find Russian websites dedicated to finding missing people. My newest find is Poisklyudei.
Of course, this site is in Russian only. However, it is free and easy to register as a user. Click on Регистрация (registration) on the top right and then click on принимаю in the blue oval below Общие правила на сайте to agree to the site rules.
Visitors can avoid filling out the registration form by using their accounts from Facebook, Yandex, Mail.Ru, Google, VK and Odnoklassniki.
If you don’t have accounts with these social networks, логин is username and пароль is password and then retype the password in the next line. The next line asks for your e-mail address and then you retype the provided code in the box.
After you are registered, click on Добавить заявку under the homepage’s search bar to post a missing person message. ФИО разыскиваемого is the name of the missing person, Место жительства, область поиска is place they lived and region being searched, Дата/год рождения is date/year they were born and кто ищет is your relationship to the missing person. Then up to three photos can be posted of the missing person. You can use Google Translate or Promt to write in Russian.
Once missing person messages are posted, users will see the number of views and the responses to their posts or can check their mailbox. Poisklyudei is almost three years old and has several hundreds of new posts each month. It is worth a try for finding missing family.