Dentist: spaces left behind in the place where top tooth were extracted.unable to continue treatment.any suggestions to fill the gap :'(?!

Yes- many options: I'm not completely clear on what was done and what your question is- "spaces for one top tooth removed? You can't continue treatment with that dentist or with any dentist? Why not? There are many methods to replace the tooth, both on a temporary and permanent basis. You will need to see a dentist to discuss your options- types of replacements\costs\pros & cons\ timeframes, etc.

Need to be evaluated: I would suggest that you see a dentist for eval but in the meantime you should wear retainers to maintain position of teeth and spaces until such time as you can complete your ortho treatment. Otherwise the teeth are just going to move any which way they want and you will end up with a mess that is difficult to treat. Invisalign or reg retainers can be made with the missing teeth incorporated in.

Prosthodontics: Although there will never be a way for dentists to truly replace what god gave you, space replacements are a different story. A prosthodontic appliance is often a very suitable low cost method for restoration (ie. Partial denture.) a bridge is a traditionally secure option that is long-lasting. And implants are top-of -the-line restorations that, unfortunately, come with an according pricetag.

Partial denture: A removable partial denture is usually the most economical interim replacement. The all resin partial is less expensive than one with metal reinforcement.

Cheapest solution : An essex retainer will at the very least keep your teeth from shifting and moving. This will allow you more options when you are ready to replace these teeth@.