拉脱维亚 - 白俄罗斯
If you want to travel from Latvia to Belarus the best option is to take the direct night train between Riga and Minsk that runs every other day. There are no other direct trains between the two countries. Tickets can be bought online from Latvian Railways or at a station.
拉脱维亚 - 立陶宛
To travel from Latvia to Lithuania by train, you have to change the train in Daugavpils, the border station. Tickets are available via the booking links or at the station. Example: calculate with about 16 Euro for a train ticket from Riga to Vilnius.