cannot access admin after log in. Role/user level seems to have changed

I use wordpress as a CMS to upload the content on my blog. I am not a specialist in any sense. From what I can tell, sometime in the previous 12 months my wordpress user level or role has been changed so that I can no longer administer the site. My server support team says they do not provide technical support for wordpress. How can I re-set the user level or role and the related permissions so I can update my blog?