Well, depends if it means your Windows drive (assuming you had them installed separately) or your Solus drive.
Does lsblk show your main drive is mounted to /? This should (normally) be /dev/sdb on a HDD/SSD, or nvme0n1p2 for an NVMe.
If either are mounted then you should be fine. If not, there are a few steps to check.
Type cat /etc/fstab and check if your root partition is mounting by default (Mine, for example. Don't worry of the "file system" column is different).
If not, then we'll quickly add it.
Type sudo blkid and check for your root partition's UUID (Again, /dev/sdb or /dev/nvme0n1p2, normally.)
UUID="8ff1ecb1-9fbb-4ebd-b3c3-2045c6a240d7", for example.
Open your editor of choice (remember to use sudo) and edit /etc/fstab.
First, paste the UUID without the quotes. Enter the mountmount (/, in this case) and then the filesystem (ext4, btrfs, etc). Then finish with defaults 0 1 to close it out. It should look something like this (ignoring the first entry).
After this, save the file and type sudo systemctl daemon-reload so that your new config is recognised. Then type sudo mount -a.
If it mounts without error, then your problem should be solved.
