There are no herbal medicines currently recognised to treat ‘loss of speech’ (from any cause, e.g. sore throat to stroke). You should also be aware that just because a medication is “herbal” does not mean it is “harmless” – i.e has no side-effects. Some herbal medications can cause kidney and liver damage, along with other medical problems, in previously healthy individuals. (The level of safety analysis on herbal medications is far lower that what is required on standard medciations.) Always use with caution.