CC3220S-LAUNCHXL: Deleted mcubootimg.bin file from UniFlash. How do I restore it?

The file is generated in the ota examples (as its structure contains the watchdog timeout to protect the test image following the OTA).

You can run the OTA example to generate the file, or just run the following code in one of your example (and of course you can create the file based on the structure given).

typedef struct sBootInfo
{
    uint8_t ucActiveImg;
    uint32_t ulImgStatus;
    uint32_t ulStartWdtKey;
    uint32_t ulStartWdtTime;
}sBootInfo_t;

int32_t Platform_CommitWdtConfig(int32_t TimeoutInSeconds)
{
#ifdef CC32XX
    int32_t lFileHandle;
    uint32_t ulToken = 0;
    sBootInfo_t sBootInfo;
    int32_t lRetVal;

    lFileHandle = sl_FsOpen(
        (unsigned char *)"/sys/mcubootinfo.bin",
        SL_FS_CREATE | SL_FS_OVERWRITE |
        SL_FS_CREATE_MAX_SIZE(
            sizeof(sBootInfo)) |
        SL_FS_CREATE_SECURE | SL_FS_CREATE_PUBLIC_WRITE |
        SL_FS_CREATE_NOSIGNATURE,
        (_u32 *)&ulToken);

    if(0 > lFileHandle)
    {
        //OTA_DBG_PRINT("OtaWatchDog: Error opening bootinfo file
      //        : %d\n\r",lFileHandle);
        return(-1);
    }

    memset(&sBootInfo,0,sizeof(sBootInfo_t));
    /* max 104 seconds */
    sBootInfo.ulStartWdtTime = 40000000 * TimeoutInSeconds; 
    sBootInfo.ulStartWdtKey = APPS_WDT_START_KEY;
    lRetVal =
        sl_FsWrite(lFileHandle, 0, (uint8_t*)&sBootInfo, sizeof(sBootInfo_t));
    lRetVal = sl_FsClose(lFileHandle, 0, 0, 0);
    if(0 != lRetVal)
    {
        //OTA_DBG_PRINT("OtaWatchDog: Failed to close the bootinfo file");
        return(-1);
    }
#endif
    //Enable WDT - done by PRCMCC3200MCUInit
    //HWREG(0x4402E188) |= 0x00000020;
    return(0);
}

and here is an example file: 

mcubootinfo.bin

br,

Kobi