How does the liver work? and once something causes raised enzymes, can it ever heal itself enough to go through it again?

Liver heals: Many things can cause temporary elevations of liver enzymes in the blood, including alcohol, medications, hepatitis, circulatory problems, etc. Unless permanent damage has been done (usually over a long time, like with alcoholic liver damage) the liver can heal itself and resume normal function.

Complicated and Yes: Liver is a very complicated organ with very many functions, too complicated to cover in a brief answer. Many causes of elevated liver enzymes are transient and liver can completely recover from it, e.g., alcohol binge, infectious mono, hepatitis a, most cases of hepatitis b, and drug toxicity.