This was my first flight on Vatsim IFR and on Virtual line duty for a VA. My attention was to much on my FMC programming, due to slightly different routing from what i get, using Simbrief  directly.
So when i was done and complete with the programming, I failed to recongize that my entire Flight was set at 5000 ft. This was discovered on climb, so I used MCP alt intervention to achieve planned flight level of 270. Sometime after TOC i encountered clouds, but the stress from the previous situation failed me to recognize that this was heavy icing condition, so i did not activate anti ice on neither engines nor wing. This shortly caused dual engine failure. I started decending imediatly while investigating. 4 or 5 restart attemps later and at flight level 140 aprox, restart was sucessful, now with anti ice engaged. I was rougly still on Lnav path, but kept speed and altitude at a level I regarded safe, as I still did not now the root cause for the failure, and/or if the aircraft had been damaged in any way. I soon got my vectors for ILS approach for 01L ENGM. 
Had to go around once due to short time from handover to tower, traffic load, and a bit of high speed on my approach. 2. attempt was all good.