On this forum, there was many times discussed an important position of Latvian language in Latvia. The Latvian officials are often supposed to declare, that Latvia is for Latvian nation only, and there's a primary position of Latvian language, which is the only official language in Latvia, and every foreigner is supposed to learn it for a wide communication. If you know Russian, in Riga and some other cities, often you'd be understood, 'cause about 1/3 of the Latvian inhabitants are native Russians, and most of native Latvians do understand and can communicate Russian - except the youth, which is supposed to know and speak mostly Latvian and a bit English. As about English, most likely only a small percent of inhabitants, except those highly educated or the other foreigners, would understand you in a public place, and would communicate with you in English.
There is a wide-spread video we have on YouTube now, which is about a conflict between some English-speaking foreigner, and a security person, happened recently on March 25th, 2018 in the "Maxima" store in Riga (141 Kurzemes str.).
On this video (and prior to the time we could watch), a self-abandoned English man is coming to the cash desk which is, primarily, intended for parents with children only. A man expressively proposes, that there are only TWO cash desks are opened, and he's not going to wait or to give his place to the mom & baby which are standing back of him. The crowd begins to attack him, some Russian-speaking young man tries to catch and hold the agressive person, this is what actually happened before the conflict with a security guard.
Further, the security guard (a Latvian "girl", or most likely, a young or middle-age woman, we can't recognize her face) starts to offensively scream to the troublemaker: "Stop to hustle! Hey, learn to speak Latvian! Can you read? Learn to read! Jackass!"[Watch/comment it on YouTube as well]
I couldn't say this is the common situation you meet in Riga, or in Latvia, in whole. But be aware, that in such public places like middle-class food stores, local workers - like the "local kings" - may intentionally not understand you, or force to teach you Latvian. Especially avoid Russian words, if you know them. Any Russian word is a stop word, specially in "pure Latvian" cities; but if you know English, be prepared being nursed by Latvian as well.