Insurers call you "high risk" when your record suggests you are more likely to claim: several at-fault accidents, serious or repeated convictions, an impaired-driving charge, a gap in coverage, or a policy cancelled for non-payment. Many standard insurers decline these files, and the ones that accept them charge much more.
You are not uninsurable. Non-standard insurers specialise in these records, and in most provinces with private auto insurance the Facility Association makes sure every licensed driver can buy the mandatory coverage. The goal is to get insured now, keep a clean record, and move back to a standard insurer as convictions and claims age off your record.