If no criminal charges were filed, then great . . . you won't have to worry about having a record, which can create problems if you're looking for a job. If criminal charges ARE filed, you should talk to a local attorney and ask about the ARD program. If the DA's office in your county agrees to accept you into the program, you will plead guilty and be put on probation. Once you have satisfied the terms of your probation and paid all fines and costs, you will be eligible to have the criminal record expunged.
As for the civil demand letter, they will probably demand that you pay for the concealed items (even though the store kept them) and they will probably tack on something like a "restocking fee." If you don't pay whatever they are asking for, then they will probably threaten to sue you in small claims court (in PA, the Magisterial District Court). As another answer advised, you WILL get through this.
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