740i Timing Chain

I heard some knocking when trying to start my 95 740i, then nothing. After many days of tracking codes, spark and fuel system checks, I removed a valve cover and found the timing chain has jumped about three damper wheel sensing tooths. Is it possible to to relieve the tensioners and move it back without removing and tearing down the engine? If it must be removed, what do you think the cost would be to put it back in proper time,as that's just too much work for me. Also, I wonder what caused it to start with and would that just reoccur?

I heard some knocking when trying to start my 95 740i, then nothing. After many days of tracking codes, spark and fuel system checks, I removed a valve cover and found the timing chain has jumped about three damper wheel sensing tooths. Is it possible to to relieve the tensioners and move it back without removing and tearing down the engine? If it must be removed, what do you think the cost would be to put it back in proper time,as that's just too much work for me. Also, I wonder what caused it to start with and would that just reoccur?
please can some one say something on this issue, my timing settings has be distorted by a technician and he cant find the right settings for the chain, please what else can be done to know the right chain settings?some one help with a step by step procedure to adjust a timing chain.my car is BMw 740i and it wont start because of wrong settings . Please i need help

Year?