Based on the facts stated by you, the matter may potentially involve both civil and criminal remedies, but the strength of the case will depend upon the exact nature of the representations made to you at the time of investment, the documents executed, the payments made, and the subsequent conduct of the person concerned.
You have stated that you invested approximately ₹7 lakhs in 2014 for a land transaction, that you possess a signed document, and that there are WhatsApp communications acknowledging receipt of money. You have further stated that after more than a decade, the person is offering a half-constructed room in Titwala which is allegedly worth substantially less than your original investment and that various documents shown to you do not stand in his name. If it can be demonstrated that from the very beginning he induced you to part with money on the basis of false representations regarding ownership, authority, or the proposed investment, the facts may support allegations of cheating and criminal breach of trust in addition to a civil claim for recovery.
Before approaching the police, it is advisable to collect and organize all available evidence, including proof of payment, bank records, receipts, the signed document, WhatsApp chats, emails, photographs, brochures, property papers shown to you, and any promises made regarding return of money, allotment of land, or transfer of property. The more documentary evidence available to show deception from the inception of the transaction, the stronger the criminal complaint becomes.
As a practical matter, the usual course is first to issue a detailed legal notice demanding either transfer of the promised property or refund of the amount with interest within a specified period. If the response is unsatisfactory, a police complaint and appropriate civil proceedings for recovery may be considered. In appropriate cases, proceedings before the Economic Offences Wing may also be explored if multiple investors have been similarly affected.
As regards the time involved, criminal complaints can result in faster pressure on the opposite party, but investigation timelines vary significantly. Civil recovery proceedings can take several years depending upon the court and the nature of the defence raised. Therefore, no responsible lawyer can guarantee a particular timeframe or result.
Similarly, it is not possible to accurately predict the "winning chances" without examining the signed document, proof of payment, and the communications exchanged between the parties. However, the existence of written acknowledgements, WhatsApp messages admitting receipt of funds, and evidence showing that the property documents did not belong to the person making the representations would certainly be relevant and potentially significant evidence.
Before taking any step, I would strongly recommend having all documents examined by a lawyer so that it can be determined whether the facts disclose a pure breach of contract, a money recovery claim, or a case involving dishonest inducement from the inception that may justify criminal action. The strategy should be based upon the documentary evidence rather than the mere passage of time since the investment was made.