I fell over and grazed my knee it hurts to move it, i want to help it heal and wondering if hydrocortisone is going to help ?

No: Sounds like an acute and not a chronic (weeks to months) problem. The best solution is to let rest, splinting, protection, heat (after a few days, ice in the first day or two), and decreased leg mechanical stress (perhaps crutches) as doctor mother nature heals. Cortizone (hydrocortisone) is useful for chronic problems. An osteopath is able to help with treatment and diagnosis.

Knee injury: If it is simply a scab, a topical antibiotic is better than hydrocortisone. Never put a steroid cream on an open wound. If the actual kneecap hurts or pain with walking an xray is warranted.