Azure VM Ubuntu, file system goes into read-only, how can I fix it?

I’m having trouble with a Azure VM running Ubuntu. The main disk is suddenly read-only, and I haven’t figured out how to solve this myself yet. I tried remounting all drives, restarting the server (both from terminal and Azure), but it didn’t help. How can I get it up and running again?

/dev/disk/by-uuid/a7c7d314-MYGUID-a7af-df2ea2ce272f / ext4 ro,relatime,data=ordered 0 0

username@server:~$ cat /proc/mounts
rootfs / rootfs rw 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
udev /dev devtmpfs rw,relatime,size=331108k,nr_inodes=82777,mode=755 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /run tmpfs rw,nosuid,noexec,relatime,size=68688k,mode=755 0 0
/dev/disk/by-uuid/a7c7d314-MYGUID-a7af-df2ea2ce272f / ext4 ro,relatime,data=ordered 0 0
none /sys/fs/cgroup tmpfs rw,relatime,size=4k,mode=755 0 0
none /sys/fs/fuse/connections fusectl rw,relatime 0 0
none /sys/kernel/debug debugfs rw,relatime 0 0
none /sys/kernel/security securityfs rw,relatime 0 0
none /run/lock tmpfs rw,nosuid,nodev,noexec,relatime,size=5120k 0 0
none /run/shm tmpfs rw,nosuid,nodev,relatime 0 0
none /run/user tmpfs rw,nosuid,nodev,noexec,relatime,size=102400k,mode=755 0 0
none /sys/fs/pstore pstore rw,relatime 0 0
systemd /sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,relatime,name=systemd 0 0