Check through your BL files and make sure they're not set to read-only.
Go to your Steam\steamapps\common\Blockland folder and try deleting the file "cache.db".
If you uninstall from Steam, do any files get left behind? (Steam\steamapps\common\Blockland)If so, can you give us a list?Delete them and try and install Blockland again.
Right click on the Blockland folder in your steam directory. Click properties. Look for "Read-Only", if it's checked, uncheck it. If it isn't come back here and we'll check more folders.
Delete ALL the files and let steam re-download everything