How do I apply for disability credit

If you are referring to the disability tax credit (DTC), I recommend speaking with Disability Credit Canada (https://disabilitycreditcanada.com/). We unfortunately don't handle DTC matters ourselves, but this group is an external organization specializing in the DTC, and will be able to assist.
If there's anything else we can help you with, please contact our disability specialist, Rebecca, at rebecca.stap@stlawyers.ca and she can direct you further.