Telegram still down. Upgrades and Service Repairs are ongoing after a massive power outage in the Amsterdam region that affected many services. Telegram users in Europe, MENA, Russia and the CIS are currently unable to connect. We apologize and will update you on the progress.

REFER: https://twitter.com/telegram/status/990474364108894209?s=19

NB: You should remember desktop client is linked to Telegram Account. DONT FORGET. Bitsum's cryptonote algo and blockchain syncs with telegram. so telegram down. Wait for service repairs and upgrade fully complete and telegram back up before you sync.